Hey I am also a 3d artist who started making games not too long ago.
Because the category of “games” is so diverse, it is really impossible to say, “this is how you should plan your project” or anything like that.
And so much will depend not just on your games goals but also you as an individual. I might organize my project one way, you could do a similar project but approach a totally different way.
So then the best thing to do is get experience under your belt. To that end, you’d want to make many small games. The intent is only to learn and gain experience so there is no stress or fear of failure. You can start out by following tutorials and once you feel ready to fly on your own you can remake classic, simple games, or rework/add onto the tutorial projects you’ve made… with enough experience like this you’ll be able to start envisioning how to tackle more unique and complex projects.
It is worthwhile to get a tutor as well. Someone available for a couple hours a week to help you troubleshoot problems and such. They don’t have to be a guru - just somebody with some experience developing games and that you communicate well with.
As far as project based tutorials go, I highly recommend gamedev.tv, and definitely exhaust everything in the unreal learn area. Their is really too much stuff available for free - you’ll start feeling ready to do your own work before you ever finish all the great and free/cheap learning content available.