Good frames are bit like good tailoring. If no-one notices it, you’ve probably got it about right.
A “statement” frame can distract from the picture. The best way to choose the right frame for your picture is to answer the question, “Do I have a picture I want to frame or a do I have a frame I want to put a picture in?”
If you’re starting with the picture, choose a subtle frame which suits the style, colour and ambience of the picture. Contemporary images and portraits usually benefit from simple frames.
If you are framing a print, you will want a mount around it as a border. Use one that is no more than half the width of the picture. Any wider will swamp it and distract.