I think 2-step stamp sets are the most versatile sets of all. I always recommend them for those starting off with stamping because you can use one set for lots of different techniques. I'll show you what I mean.
In a 2-step stamp set you get an outline image and a base image. The idea is that you stamp the outline, and then stamp the base image over the top (or vice versa). The base image does the colouring-in for you. It's quick and easy to produce really effective results. Don't worry about trying to line them up perfectly. It adds movement and interest when they are slightly out of alignment (at least that's my story and I'm sticking to it!). Here's a card I made using this technique with the "Botanical Blooms" Sale-a-Bration set: Now just because this is a 2-step stamp set doesn't mean I have to use it that way. Here I've used just the outline stamps, stamped them onto patterned paper and cut them out. Then I've stamped the same images onto some plain cardstock, and paper pieced my cut-outs over the top of some stamped images:
stamps: Botanical Blooms, linen
ink: Certainly Celery, Perfect Plum, So Saffron, Versamark, Chocolate Chip, Black Stazon
card: Certainly Celery, Whisper White, Perfect Plum, Groovy Guava,
other: Wide Celery ribbon, Afternoon Tea DS paper, Certainly Celery Prints DS paper, Rich Regal brads, Word Window punch, 1 1/4" Square punch, Rich Regal markers, Soft Subtle markers