I am a huge fan of using blocks when practicing yoga. They are often used by beginners and those with injuries to help them modify certain postures, but they are also used by experienced and flexible yogis as tools to get deeper into poses.
Blocks come in many shapes, sizes, and they can be made out of many different materials including cork, foam and bamboo. If you're not sure where to begin, get a 4 inch yoga block and start with that. Once you learn ways to use it, you can figure out of you need to add more blocks to your home studio.
Here's a basic list of the different kinds you can get.