The easiest way to go about business is to first take a look at a couple of "givens." If you've got a high pH and hard water, I would rule out fish that need soft, acidic water. You also can't keep fish that won't fit in your tank. Unfortunately for you, that means most fish from Amazonia (i.e. most tetras, many of the more popular catfish like corydoras and plecos, discus, etc.). Many fish from SE Asia also like soft, acidic water (barbs, loaches, some other types of catfish, rasboras, etc.). Livebearers do really well in hard water, though, as do African rift lake cichlids and assorted other species such as some of the danios, some rainbows, etc. Many fish are quite adaptable so just how hard and alkaline your water is can be a deciding factor in risking softwater fish or not.
For general community tanks, I like to stock a school of fish for the bottom, another for the middle and fish for up top along with a few fish that can be kept singly or in pairs as "centerpiece" fish. I wouldn't keep any fish that grows longer than about 6" in a 29g tank. Other than those general guidelines, it's hard to give suggestions as there are a lot of fish in the sea (or in rivers and lakes, in the case of freshwater).
If you're looking for stocking ideas, have a look through some of our fish profiles and see what sorts of fish catch your fancy: http://www.tropicalfishkeeping.com/profiles/