FRAMING TIPS
Tip #1 - Don't spend a ton of money
You do not have to spend a lot of money to frame your art!
Tip #2 - Always mat to a standard frame size
If you are matting and framing a photography, the photography can be any size, but the mat size should be to a STANDARD frame size. Standard frame sizes are generally common (google it) but an easier way to approach the problem is to buy the frame first. Then, purchase your mat.
Tip #3 - Buy frames at non-frame shops
USA: I recommend Michael's as a first choice for framing. It is a national store and you should have one in your area. If not, Target is a decent second option.
Germany: I recommend Obi for basic frames. (Obi also does matting)
Outside the USA or Germany: I recommend "do it yourself" or "craft/art" stores for basic frames.
Tip #4 - Go to Frame Central for your matting needs
If you are in the Portland, Oregon area -, go to Frame Central. They offer on demand matte cutting and standard frames. You can walk in with your art, and walk out with a matte and frame that fit. If you do not have supplies at home for framing (a space, tape, canned air) and a fair amount of patience for dust removal, I highly recommend that you pay them to assemble the piece.
If you are not in Portland, Oregon, again, I recommend "do it yourself" or "craft/art" stores for a place that will custom cut your matte.