Try to look at completed works and study how they were done some people who complete stuff show their processes. Also, there’s definitely tutorials out there that help with doing more than crates and barrels. The biggest advice I can give is to have good reference material–no good artist can do things from scratch without reference. Look at any behind the scenes stuff and they always do extensive reference.
As for drawing–you don’t need drawing as a 3D artist, it won’t hurt but you can be an amazing 3D artist who can’t draw very well.