Mixing foundations? Drugstore + Sephora brands

Hello all!

 

I am a frugal b😘h  who can't break away from the tried-and-true Maybelline Fit-Me foundation. It has everything I am looking for, medium-coverage, buildable, oil-free... But I am looking to spice it up a bit with something fancier. 

 

What foundations can I mix in to create a perfect medium-coverage that stays lightweight and luminescent? (And, who knows, maybe I'll take the plunge and use the $$ product as my go-to!)