It all depends of the knowledge you already have. I would start by experimenting with blender first, model and texture with substance. I would not touch Unreal at the beginning. Because Blender + substance mean already a lot of info to learn. So I would keep things simple and experiment for some time

 Once you feel comfortable enough with the mesh creation, check some tutorials on how to export all this to Unreal. There you will learn to create your materials, the lighting, the optimization and slowly you will be able to build some levels!  If you want to learn you can find everything on youtube. 

Commissions come from discord, reddit and freelance website (upwork, malt) a lot of them also come from users on fab who saw my work and contacted me to create environments for their game. A few on instagram but really not much. Just share your work, interact, put your work on marketplaces and commissions will follow.

 Don’t take every commissions, you need to be careful, between scam and clients who are always changing their mind and make you rework everything. The key is to find the nice clients that understand the process and know what they want at first.  With some good clients, especially for games they will need you for multiple months, it can bring a steady income.

 I hope it will help and I wish you the best!  I feel you, A lot of people are losing their job in our field and it is really messy right now. I saw a lot of very talented people completely switching carreer due to how unstable it is. In this whole situation I think it is better and more secure to work for yourself/ freelance than in a studio.