Basswood is great but if you have access to thick cottonwood bark, it's a good and cheap {free} choice as well. Repetition / practice is how to develop any skill and working with a soft medium allows you to carve a particular figure twice as many times per week as does a harder medium.
try pine/white wood(spruce) availiable at any hardware store allready dried. keep your tools sharp! dull tools only cut fingers and hands,lol. good luck .have fun.