I went shopping for pots and little of what I saw was to my taste. Anything remotely acceptable was very expensive. I could do my own decoration but I worry about what media to use given that water will be transpiring in and out of the pot. I could do my own pots with composition leaf ("gold" leaf) but I worry that even when it's sealed with gilding sealant, the water coming at it from the back will tarnish it (not a problem with real gold but I can't afford real gold).
Modifying terracotta and other pots
Spidra,
The best sealant for terra cotta is waterproofing concrete primer & paint, both inside and out (or just inside the pot). I am not sure of the compatability with the other paints you are planning on using. Some paints, like latex and oil base with not stick to each other. Usually water base will stick to water base & oil base to oil (but not always). I would suggest you try a small shard sample first.
I've just just put my first container garden together, so it's still a work in progress. I have a permanent base area that's about 20'x20' with wood chip mulch, granite rocks, and solar lighting (both rotating colors & white), and I'll be rotating the plants for the seasons.
I haven't gotten to this yet, but I plan to buy material remnants (cotton is very cheap) to wrap my plain planters in. I'll be color coordinating it for the house and/or season, and changing it probably at least every year, if not more. The cotton will allow drainage & wear well thru the water, although it'll probably bleach out from the sun by the end of the summer, but I don't care since it'll give me a chance to change it. ;) Just cut a circle or square, wrap up to the top and put a large rubber band or nylon tie to hold it in place, adjusting the ruffles. It might be a good idea to prewash the material in hot & dry it on hot, to avoid any excessive shrinking in the garden when it gets wet & dries in the sun.
Spidra........I paint my pots all the time, so far they have done very well. I use a primer if they are too glossy of a surface before I spray paint them.
I also have spackled planters that I didnt like and "re-shaped" them, or stuck ornamentation in them that I yanked off of something else. I find all sorts of vases, bowls, and planters at garage sales that can become something else.
I don't usually do terracotta planters though....
I just used enamel spray paint on my terra cotta pots and it seems to work just fine. One of my large terra cotta pots had broken in half, so I glued it back together, strapped it with large tie-wraps and painted over everything, inside and out (I did use a coat of spray primer first). That was about 4 years ago and the pot is still just fine.
And if you find a plastic pot that you like, but aren't happy with the color, or just want to jazz up an old nursery pot, there's this wonderful spray paint from Krylon called "Fusion" that is made especially for plastic. It bonds to the plastic. I tried it when it first came out and the pots I painted are still in good shape, no chipping or peeling.
Here's my broken pot:
