Formal:
* शुभ यात्रा! (Shubh yatra!) - This is the most common and polite way to wish someone a safe journey.
* सुरक्षित यात्रा करें! (Surakshit yatra karein!) - This means "Have a safe journey!" and is more direct.
Informal:
* सफर की शुभकामनाएँ! (Safar ki shubhkamnayein!) - This means "Best wishes for your journey!"
* खुशहाल सफ़र! (Khushhaal safar!) - This means "Have a happy journey!"
You can also add a personal touch by saying:
* ध्यान रखें (Dhyaan rakhein!) - Take care!
* जल्दी वापस आना (Jaldi vapas aana!) - Come back soon!
The best choice will depend on your relationship with the person and the formality of the situation.