Here's a radical thought: Tie up yourself first!

Of course it's pretty hard to tie that final knot on yourself, but apart from that you can learn a great deal about knots and ropes on your own. Tying a person down with ropes can be downright dangerous and at least very painful if you don't know what you're doing. You need a fundamental knowledge of ropes vs. the human body before you can subject others to your masterful art.

Try tying your legs firmly together for several hours for starters. Crawl around to floor a lot, and you'll immediately know a lot more about what to do and what not to than any brief advice could teach you.

Good luck!