I will agree that the Rail Fence is a great pattern for beginners. It uses 3 colors, has only straight cuts, and goes together fairly easily. You want to make something you'll use, so a wall hanging or lap quilt would be great. Everyone else is correct that this habit gets expensive, start with the basics: ruler, rotary cutter, mat, scissors, thread, and fabric. On the rulers several of us recommend picking a brand that you find useful and easy to use, and stick with that brand. This may be somewhat limiting if you shop local, but you can find most anything on the internet. Be sure to post pics when you're done.
Darren