Willow Leaf Ficus (ficus nerifolia/salicafolia)
First of all, bonsai trees are either "feminine " or "masculine." Most pines are considered to be masculine, if they don't do a lot of bending and curving. A masculine tree will be one that sort of comes to a point, rather than having lots of branches going here and there.
Lots of curves and twists and spreading branches generally dignify a feminine bonsai. Most deciduous trees would be though to be feminine trees. This is not a hard and fast rule, as modern bonsai growers are rarely tied to strict tradition.
Unglazed Ceramic Pot
But traditionally a masculine pot will be earth toned and either fully or partly unglazed, and most likely textured. A feminine pot will be a glazed pot, perhaps with decorations or carvings. A feminine pot can be many different subtle colors, like red or blue or green. A pot with legs or feet helps with drainage, which is vital to the health of the bonsai tree.
Blue Hexagon Shape Ceramic Bonsai Pot
There are experts that say that the only pot for a bonsai is an unglazed one. That the roots need something to hold on to. Others say it doesn't matter. Read a good ebook on bonsai care to learn as much as you can about the subject of pots.
Houtoku Pot, Rust Colored
There are pots with legs and pots without legs, and they come in all shapes.
Before you choose a pot, plan in your head or on paper exactly what you hope your bonsai will eventually look. In a rectangular pot, the depth should be equal to about 2/3 of the height of the above ground tree. Some like to limit the depth of a round or oval pot to as little as 1/3 of the above ground tree height. Get some expert advice on this, as it is important, and the depth varies with species and pot shape and size.
Choose the color and shape according to your vision of what the plant should become.