It is narrated from Imam (a.s.) that he said: When you have made a firm intention to travel, perform ablution and pray two rak'ats:
In the first rak'at, recite Surah Al-Hamd and Surah Ar-Rahman, and in the second rak'at, recite Surah Al-Hamd and Surah Al-Waqi'ah or Surah Tabarak (Al-Mulk).
If it is not possible for you to recite these surahs, then recite any surah you wish (according to how much time you have), then supplicate to Allah with this prayer:

بِسْمِ اﷲِ الرَّحْمٰنِ الرَّحِیْمِ

Bismillaahir-Rahmaanir-Raheem

In the name of Allah the Beneficent the Merciful.

اَللّٰھُمَّ إِنِّي خَرَجْتُ فِي سَفَرِي هذَا بِلا ثِقَةٍ مِنِّي بِغَيْرِكَ، وَ لَا (رَجَاءٍ يَأْوِي إِلّا) إِلَيْكَ، وَلَا قُوَّةٍ أَتَّكِلُ عَلَيْهَا، وَلَا حِيلَةٍ اَلْجَأُ إِلَيْهَا إِلَّا طَلَبَ فَضْلِكَ وَابْتِغَاءَ رِزْقِكَ، وَتَعَرُّضاً لِرَحْمَتِكَ، وَ سُكُوناً إِلى حُسْنِ عِبادَتِكَ. وَأَنْتَ يا اِلهِي أَعْلَمُ بِمَا سَبَقَ لِي فِي سَفَرِي هذَا، مِمَّا أُحِبُّ وَأَكْرَهُ وَلِمَا أَوْقَعْتَ عَلَيَّ فِيهِ قَدَرَكَ، وَمَحْمُودَ بَلَائِكَ فَأَنْتَ يَا اِلهِي تَمْحُو مَا تَشَاءُ وَتُثْبِتُ، وَعِنْدَكَ أُمُّ الْكِتَابِ

Allāhumma innī kharajtu fī safarī hādhā bilā thiqatin minnī bighayrika wa lā rajā'in ya'wī illā ilayka wa lā quwwatin attakilu ‘alayhā wa lā ḥīlatan aljā'u ilayhā illā ṭalaba faḍlika wa btighā'a rizqika wa ta‘arruḍan li-raḥmatika wa sukūnan ilā ḥusni ‘ibādatik. Wa anta yā ilāhiya a‘lamu bimā sabaqa lī fī safarī hādhā mimmā uḥibbu wa akrahu wa limā waqa‘ta ‘alayya fīhi qadarak wa maḥmūda balā'ik fa anta yā ilāhiya tamḥū mā tashā'u wa tuthbitu wa ‘indaka ummu al-kitāb.

O Allah, I have set out on this journey without trust in anyone but You, without hope except in You, without strength to rely upon, without means to resort to except seeking Your grace, pursuing Your provision, exposing myself to Your mercy, and resting in the beauty of Your worship. You, O my God, know best what has preceded for me in this journey of what I love and hate, and what You have decreed upon me therein, Your praised trial. You, O my God, erase what You will and affirm, and with You is the Mother of the Book.

اَللّٰھُمَّ صَلَّ عَلَى مُحَمَّدٍ وَآلِ مُحَمَّدٍ، وَاصْرِفْ عَنِّي فِي سَفَرِي هذَا كُلَّ مَقْدُورٍ مِنَ الْبَلاءِ، وَادْفَعْ عَنِّي كُلَّ مَحْذُورٍ، وَأَسْبِلْ عَلَيَّ فِيهِ كَنَفَ عِزِّكَ وَلُطْفَ عَفْوِكَ وَرَحْمَتِكَ، وَ حَقيقَةَ حِفْظِكَ، وَسَعَةَ رِزْقِكَ، وَتَمَامَ نِعْمَتِكَ

Allāhumma ṣalli ‘alā Muḥammadin wa āli Muḥammadin wa aṣrif ‘annī fī safarī hādhā kulla maqḍūrin mina al-balā'i wa dfi‘ ‘annī kulla maḥdhūrin wa asbil ‘alayya fīhi kanafa ‘izzika wa luṭfa ‘afwika wa raḥmatika wa ḥaqīqata ḥifẓika wa sa‘ata rizqika wa tamāma ni‘matik.

O Allah, send blessings upon Muḥammad and the family of Muḥammad, and turn away from me in this journey every decreed affliction, avert from me every feared harm, and spread over me therein the wing of Your might, the gentleness of Your pardon, Your mercy, the reality of Your protection, the expanse of Your provision, and the completion of Your favor.

وَافْتَحْ لِي فِيهِ أَبْوابَ جَمِيعِ فَضْلِكَ، وَعَطَائِكَ وَاِحْسَانِكَ، وَأَغْلِقْ عَنِّي أَبْوابَ الْمَخاوِفِ كُلِّهَا وَ جَمِيعَ مَا أَكْرَهُ وَأَحْذَرُ وَأَخَافُ عَلَى نَفْسِي وَأَهْلِي وَذُرِّيَّتِي، وَافْتَحْ لِي أَبْوَابَ الْأَمْنِ كُلَّهَا، وَاصْرِفْ عَنِّي الْهَلَعَ وَالْجَزَعَ، وَ ارْزُقْنِي الصَّبْرَ وَالْقُوَّةَ وَالْمَحْمَدَةَ لَكَ، وَالنَّجَاةَ مِنْ كُلِّ مَحْذُورٍ وَمَقْدُورٍ ، بِمَا أَنْتَ اَعْلَمُ بِهِ مِنِّي، وَ اجْعَلْ ذَلِكَ خِيَرَةً لِي فِي آخِرَتِي وَ دُنْيَايَ، وَ أَسْأَلُكَ يا رَبِّ أَنْ تَحْفَظَنِي فِيمَا خَلَّفْتُ وَ رَائِي مِنْ أَهْلِي وَمَالِي وَمَعِيشَتِي وَ صُنُوفِ حَوائِجِي

Wa ftḥ lī fīhi abwāba jamī‘i faḍlika wa ‘aṭā'ika wa iḥsānika wa aghliq ‘annī abwāba al-makāwifi kullihā wa jamī‘a mā akrahu wa aḥdharu wa akhāfu ‘alā nafsī wa ah lī wa dhurriyyatī wa ftḥ lī abwāba al-amni kullahā wa aṣrif ‘annī al-hal‘a wal-jaz‘a warzuqnī aṣ-ṣabra wal-quwwata wal-maḥmadata lak wan-najāta min kulli maḥdhūrin wa maqḍūrin bimā anta a‘lamu bihi minnī waj‘al dhālika khiyaratan lī fī ākhiratī wa dunyāyā wa as'aluka yā Rabbi an taḥfaẓanī fīmā khallaftu wa rā'ī min ah lī wa mālī wa ma‘īshatī wa ṣunūfi ḥawā'ijī.

Open for me therein the doors of all Your grace, gifts, and kindness, and close against me the doors of all fears and everything I hate, beware of, and fear for myself, my family, and my progeny. Open for me all doors of security, turn away from me panic and despair, grant me patience, strength, praise for You, and salvation from every feared and decreed harm, by what You know better than I. Make that the best for me in my Hereafter and my world. I ask You, O Lord, to preserve for me what I have left behind and what is after me of my family, wealth, livelihood, and kinds of needs.

يَا مَنْ لَيْسَ فَوْقَهُ خَالِقٌ يُرْجى، يا مَنْ لَيْسَ دُونَهُ رَبِّ يُناجي يا مَنْ لَيْسَ غَيْرَهُ إِلهُ يُدْعَى، يا مَنْ لَيْسَ لَهُ وَزِيرٌ يُؤْتى يا مَنْ لَيْسَ لَهُ حاجِبٌ يُغْشَى يَا مَنْ لَيْسَ لَهُ بَوَّابٌ يُرْشى يا مَنْ لَيْسَ لَهُ كَاتِبٌ يُدَارى، يا مَنْ لَيْسَ لَهُ تَرْجُمَانٌ يُنَادى يا مَنْ لا يَزْدَادُ عَلَى كَثْرَةِ السُّؤالِ إِلَّا كَرَماً وَجُوداً صَلِّ عَلَى مُحَمَّدٍ وَآلِ مُحَمَّدٍ، وَاجْعَلْ لِي مِنْ أَمْرِي فَرَجا وَمَخْرَجًا، وَارْزُقْنِي (في سَفَرى هذا) - الأَمْنَ مِنَ الْمَخَاوِفِ كُلِّهَا، وَالْغَنِيمَةَ وَالظَّفَرَ بِكُلِّ غَرَضٍ، وَبَلِّغْنِي جَمِيعَ أَمَلِي وَمَقْصُودِی

Yā man laysa fawqahu khāliqun yurjā yā man laysa dūna-hu rabbun yunājā yā man laysa ghayrahu ilāhun yud‘ā yā man laysa lahu wazīrun yu'tā yā man laysa lahu ḥājibun yughshā yā man laysa lahu bawwābun yurshā yā man laysa lahu kātibun yudārā yā man laysa lahu tarj umānun yunādā yā man lā yazdādu ‘alā kathrati as-su'āli illā karaman wa jūdan ṣalli ‘alā Muḥammadin wa āli Muḥammadin waj‘al lī min amrī farajan wa makharajan warzuqnī fī safarī hādhā al-amna mina al-makhāwifi kullihā wal-ghanīmata wal-ẓafara bikulli ghaḍin wa ballighnī jamī‘a amalī wa maqṣūdī.

O He above Whom there is no Creator to be hoped in, O He besides Whom there is no Lord to be supplicated, O He other than Whom there is no God to be called upon, O He Who has no vizier to be approached, O He Who has no gatekeeper to be veiled by, O He Who has no porter to be bribed, O He Who has no scribe to be deceived, O He Who has no interpreter to be called to, O He Whose generosity and giving increase with much asking—send blessings upon Muḥammad and the family of Muḥammad, make for me relief and exit from my affair, and grant me in this journey security from all fears, booty, and victory in every aim, and fulfill for me all my hopes and objectives.

اَللّٰھُمَّ وَكُلَّ مَنْ قَضَيْتَ عَلَيَّ بِلِقَائِهِ مِنْ أَحَدٍ مِنْ خَلْقِكَ الَّذِينَ جَعَلْتَ لِي إِلَيْهِمْ حَاجَةً وَ شُغلًا، فَخِرْهُ لِي، و اعْطِفْ بِقَلْبِهِ عَلَيَّ، وَوَفِّقْهُ لِمَا أُرِيدُهُ وَابْتَغِيهِ وَامُلُهُ، وَاحْرُسْهُ عَنْ قَصْدِي وَالْوُقُوفِ فِي حاجَتِي وَامْنَعْهُ عَنْ ظُلْمِي وَأَذَايَ، بِرَحْمَتِكَ يَا أَرْحَمَ الرَّاحِمِينَ.

Allāhumma wa kulla man qaḍayta ‘alayya bil iqā'ihi min aḥadin min khalqika alladhīna ja‘alta lī ilayhim ḥājatan wa shughlan fak hirhu lī wa i‘ṭif biqalbihi ‘alayya wa waffiqhu limā urīduhu wa btighīhi wa amūluhu wa ḥrus-hu ‘an qaṣdī wal-wuqūfi fī ḥājatī wa imna‘hu ‘an ẓulmī wa adhāyā birḥmatika yā arḥamar-rāḥimīn.

O Allah, and everyone whom You have decreed I meet from Your creation whom You have made my need and concern for—make him gentle to me, incline his heart towards me, make him successful in what I want, seek, and hope for, guard him from my intent and standing in my need, and prevent him from wronging and harming me, by Your mercy, O Most Merciful of the merciful.

Then prostrate yourself and ask for whatever you need, and then raise your head from prostration and recite this supplication:

أَشْهَدُ أَنْ لَا إِلهَ إِلَّا اللهُ وَحْدَهُ لَا شَرِيكَ لَهُ، وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ اَللّٰھُمَّ فَاطِرَ السَّمَاوَاتِ وَالْأَرْضِ ، صَلِّ عَلَى مُحَمَّدٍ وَآلِ مُحَمَّدٍ وَافْعَلْ بي مَا أَنْتَ أَهْلُهُ، وَأَدْخِلْنِي فِي كُلِّ خَيْرٍ أَدْخَلْتَ فِيهِ مُحَمَّدًا وَ آلَ مَحَمَّدٍ، وَأَخْرِجْنِي مِنْ كُلِّ سُوءٍ اَخْرَجْتَ مِنْهُ مُحَمَّدًا وَ آلَ مُحَمَّدٍ وَامْنَعْنِي مِنْ أَنْ يُوصَلَ إِلَيّ سُوءً أَبَدًا، وَلا ( تُغَيِّرُ مَا أَنْعَمْتَ عَلَيَّ أَبَداً يَا أَرْحَمَ الرَّاحِمِينَ.

Ashhadu an lā ilāha illallāhu waḥdahu lā sharīka lah, wa ashhadu anna Muḥammadan ‘abduhu wa rasūluh. Allāhumma fāṭiras-samāwāti wal-arḍi ṣalli ‘alā Muḥammadin wa āli Muḥammadin wa if‘al bī mā anta ahluh, wa adkhilnī fī kulli khayrin adkhalta fīhi Muḥammadan wa āla Muḥammadin, wa akhrijnī min kulli sū'in akhrajta minhu Muḥammadan wa āla Muḥammadin wa imna‘nī min an yūṣala ilayya sū'an abadan, wa lā tugayyir mā an‘amta ‘alayya abadan yā arḥamar-rāḥimīn.

I bear witness that there is no god but Allah alone, without partner, and I bear witness that Muḥammad is His servant and Messenger. O Creator of the heavens and the earth, send blessings upon Muḥammad and the family of Muḥammad, and do with me what befits You. Admit me into every good into which You admitted Muḥammad and the family of Muḥammad, bring me out from every evil from which You brought out Muḥammad and the family of Muḥammad, prevent any evil from reaching me ever, and do not change what You have bestowed upon me ever, O Most Merciful of the merciful.