Painting cabinets yourself is cost-effective -- a few gallons of paint, sandpaper, cleaner -- but the process is time-intensive. You can paint most cabinet surfaces, but proper prep is key to success. For laminate and melamine finishes, be sure to rough up the surface with 150-grit sandpaper, and apply a good bonding primer before topping it off with the color of your choice.
For knobs on a cabinet with a stile, like Shaker-style cabinets, allow the stile to be a guide for hanging the knob. If the knob is too large to comfortably fit in the corner where the two stiles meet, then hang the knob centered on the vertical stile, with the bottom edge of the knob aligned with the top of the intersecting horizontal stile. (Or the top of the knob aligned with the bottom of the stile, for lower cabinets). The knobs in this kitchen from Ivory Lane are a good example.
Generally speaking, I like to see a combination of knobs and handles/pulls. Knobs or handles for the doors and handles or pulls for the drawers. If you are painting your kitchen, the extra holes can be filled, sanded, and smoothed prior to painting so you can start with a clean slate and choose any hardware for your update. I say “generally speaking” because lately I’m drawn to kitchens that have all handles like this “before” photo of a kitchen we recently updated.