I posted this earlier in another thread. My answer to you is tutorials, a lot of tutorials, and practice. A great tutorial I highly recommend is Environment Creation In Unreal Engine 4. Which you can find it here: https://www.uartsy.com/course/environment-creation-in-unreal-engine-4 Also, I highly advise listening to game…
In addition, DigitalTutors/Pluralsight has some decent tutorials for games modelling/texturing, etc. =) Arimus3D has lots of great, free content on his YouTube channel for modelling in general as well.
I wouldnt recommend any of the paid online stuff for starter. Try to find someone who can show you, directly, side by side. Ideally, a senior. It will most likely not be free but you will learn much faster and be less confuse about the process. Online tutorial have too much stuff going on and I would recommend it with a…
If you want something that's handholding that's online, I really recommend getting a subscription to 3Dmotive and working through the straight forward asset making tutorials. They will hand hold you and will teach you the basics. As well, post your WIPs and work here so we can help you along and marvel at your progress.…