A lot of carvers use Basswood because it is very consistent and does not give you the problems of some woods that have a strong grain.
Jelutong and Tupelo woods are also good in this respect. If you have seen a cross section of a tree, you have noticed the annual rings, which indicate seasonal growth where growth is slower in the winter and greater in the summer. The slow growing wood is denser, and the summer wood can be a lot less dense, especially in wet years.
If you want to experiment with pine-- like sugar pine or white pine, you want to select a piece of wood that has a tight grain-- the rings are close together. This is especially true if you are using hand tools. (Sugar pine can be a little 'sappy', too.)
Some hard woods like Walnut or even Manzanita are very beautiful for sculpture, but they almost require power tools (and a good dust mask). Look for my hub about Manzanita-- to see some of my husband's woodcarvngs.
Make sure you know the qualities of your wood-- especially if you are making a lot of dust-- some of them can be toxic to breathe the dust.