Subject matter is the most obvious way to make a portfolio cohesive. I'm facing the challenge of trying to cherry pick my very best work for a portfolio, and I'm picking from a few different "mini-projects" so the look is different. Some are square, some are from 6x7 negs, and some are 6x6 Holga.

What they have going for them is that they're nearly all graphically very strong, ie. geometry and lines dominating the composition. They're obviously not from the same project though, where some are macro studies of concrete, some are the undersides of bridges, and some are farris wheels and giant clear balls with people in them (a variety I tell you!)

Can these be successfully combined in one portfolio? What will hold them together? Are similar sizes and printing/toning enough? Or should I be thinking in terms of singular projects and leave off what I might consider my best work?

I know it's tough to judge without seeing photos, but I don't have much in the digital realm, so we can talk in generalities! I'd be interested in hearing opinions from people who have submitted work to galleries or portfolio evaluations, or especially those who do the evaluating.

Thanks so much!
Chris