OK here goes:
[1] You don't need to buy a color wheel unless you want to spend the money. There are several you can download free.
[2] Even with a color wheel your material might look different because of the print size and texture.
[3] Ditto Jan in VA's advice. Look around and see what you like.
[4] Make it a fun process and you'll surprise yourself.
[5] However, remember as we 'mature' our vision may not be giving us proper feedback on color. Check with trusted friends. If your color vision is off see an ophthomologist!!!
Ex: one of my best friends wasn't aware of her miss matching colors. Her family noticed but didn't say anything. Only 2 of us quilting buddies gave her feedback and went material shopping with her. See saw her ophthomologist regularly never telling him of her color concerns and he told her she didn't need cataract surgery just yet. So she followed his advice and did nothing. Finally she listened to us and told the eye doctor of her color problems and has now had her first cataract surgery. The world is much brighter and vivid now.
Hope this all helps,
ali