You are bad at modeling, and want to get better (to make spaceships). Added difficulty of your end game being use for real time rendering, requires simpler models.

Your approach is to make many many bad models until you get good. What you’ve learned:

• Use bool tool add on (free) in Blender. Use “Brush Boolean” to make non-destructive changes.
• Use bevel modifier to make basic shapes look less basic.

This very fast video put you on to bool tool and touches on edges for making manageable UV maps: https://www.youtube.com/watch?v=zit7UmzcSgU