I personally learned a lot by messing in Cheat Engine, it is way more capable than I thought, specially because I mostly used it as a kid and never looked back.

It is a great tool to get started with assembly in my opinion because the disassembler is good enough and you can write what they call 'assembly scripts' which provides the foundation on doing memory patches in x86 asm. Then from that you can start writing your own utils to patch the games at your own will.

You can do crazy cheats by patching the game just with Cheat Engine!