I try to remember lyrics and chords. Try to remember not to pick my nose on stage.
Seriously, as others have said, you must read the audience, try to find out what they really want, and then MAKE THEM BEND TO YOUR WILL!
No, really seriously, in most places they want to hear songs they know or remember and can dance to. The beat and tempo of the song must be accurate, the rest of the performance can be really personalized the way you want.
You can look at the ages of the audience and usually guess what era their musical favorites are from.
After all these years, I've pretty much learned what will work in most situations.
I do play some instrumentals but they are almost always songs that were HITS as instrumentals, such as Last Date, Dr. Zhivago, Yakity Sax, Tuff, Wonderland By Night, Honky Tonk, Tequila, etc.
Almost all my work is done by using styles and playing right-hand fills and solos, while using both feet to activate sustain, vocal harmony, fills, breaks. As an added bonus, I've found it is difficult to pick your nose when all of your appendages are busy.
DonM