I'm making a small game, and I've found some free sound effects that I'd like to use.

The issue is that I can't get the sound effects to sound like they "belong" in my game. I don't know what to look for that can make sound effects match the rest of my game style.

I have some ideas on what affects the meshing of audio with graphics. For example, I have a feeling that the current SFX I may be too "realistic" for my graphical style, which is pretty cartoon-like. Also, is there a golden standard for what volume various SFX should be at? (for example, I am thinking that footsteps or other common sounds should be at barely audible volumes, while enemy deaths or something that is a "big deal" should be louder).

I found a similar question about graphics, I'm looking for a similar response with sound effects.