In addition to many little gardens around the yard, I do quite a lot of container gardening. I'll use everything from an old beat up washtub (such as the one above, housing catnip with a bad ass guard gnomess to protect it), to terracotta pots to plastic pots to an old tin bucket. I really like grouping containers of different sizes together, with random heights and widths.
I've learned to stick with similar colors (lots of greens and natural "terracotta") with some happy brights thrown in (predominantly purple family shades, funnily enough). I do have a random striped container or two, but again, they are in the same color families as the rest of the pots. Once the plants start filling in and taking off for the growing season, it looks really great. I have high hopes for my cardoon plants (in the large terracotta pots), which should add some dramatic height to the arrangement. This group is a mix of fragrant, lemony herbs and heirloom balcony mix petunias--which are supposed to have a beautiful, sweet fragrance. Since they will be in bright sun near the front door, I think they'll be just the thing to greet my guests this summer.