Modeling:

• if you ever found ugly faces (holed or overlapped) try to run "rewrite normals" from left-click menu and usually it will fix this.

Texturing and unwrapping:

• Texturing game assets is tricky part and needs your focus, if u need optimal performance you use trimsheets for most of your props, and if you making stylized art and need to make all details in one texture for lots of props then Texture Atlas is the way (combining all uv maps of group of objects together in one texture and one material also to reduce cpu draw calls) but avoid ceiling 2k textures on old gpu and 4k at max on moderate gpu not to bottleneck it.
• Unwrap before any deform-sculpt or subdivide modifier, it is easier to control and uv data wont be affected later !
• Morgana 3D app can actually bake Ambient occlusion in vertex color mode which doesn't require a texture nor UV unwrapping at all !
• Modifiers like Box deform, cylinder deform in morgana 3d  can actually twist your model and bend it by moving rotating selected vertices !
• In Morgana 3D you can bake Global illumination as vertex color also (the more your model is high poly the more it looks great -depending on vertices around)
• In Game Dev : Always use texture atlas(multiple textures in one image under each other or beside each other) in uv map for things that are bigger and takes a huge part from screen then make you uv island repeat around it (unwrap outside uv canvas).