With the gallery wall below, I had my friend choose her favorite pieces that were all in frames that are gold. I really encourage the use of matching frames or frames in the same color because I think it lets the art really stand out and it looks like a collection.
I also strongly encourage laying your art on the floor to develop a pattern so you get a feel for the general plan. And lastly, try starting with the center of your pattern or middle row and work your way out.