If you're extremely particular or fussy, you're picky. A picky eater might only eat chicken nuggets and tater tots.
When you invite your picky friend to dinner, you'll probably have a hard time deciding what to serve, since she hates all vegetables; and if you're picky about sleeping in a comfortable, clean place, you might not be a fan of camping. Picky people are hard to please — they like things to be a certain way. This informal word first appeared in the 1860s.