I taught myself a new key today, Db, with five flats. When I learn a new key what I do is to figure out the major 7 tonic chord, then go and figure out what each of the other six chords will be for that key. I tried to learn Gb yesterday, but it was difficult because I didn't know Db well enough. D flat is a very warm key that I like a lot. It gives me knew ideas to play in that key, and I came up with a nice sounding melody this morning.
Every key, following the circle of fourths or fifths, will have one different note, so learning a key that is a fourth or fifth from a key you already know will be easy because a lot of it will be the same.