wow - not a lot of time to prepare if you're not sure of some stuff.

Light bdsm? OK, how about starting with a collar or collar and leash. Just being collared has such an emotional effect but to put a leash on your sub as well....

Learn some very easy tying techniques. You don't mention how much experience you have in the arena, but binding is about restricting movement, not restricting blood flow. Some good info can be gathered from TwoKnottyBoys. One of those is JD, his tribe page is at: people.tribe.net/jaydee. On his page you'll see links to some of their instruction videos, etc. I've gone to their classes and some of the stuff you learn in 3 minutes. Get a piece of rope and watch some of the videos. (you can also go to their site, www.knottyboys.com and free download their instructional videos).

Surrender and abandonment: If the two of you will be inside, say, your home or hers, she should not be allowed clothes or possibly just panties. You pick them out for her.

All have to be measured against how you feel her response will be, of course. You're both old enough to know this can be a long lasting thing, especially being best friends already. It could also end quickly if she decides (or thinks) that you are too kinked for her.

Let us know how it goes.

My loves favourite to hate is hands behind.
They don't need to be tied, just, at that point where things are starting to simmer, wrap a cord or scarf around her wrists and place the ends in her palms and close her fingers over them.
This gives her time to accept your dominance and learn that she can trust you.
When she's hot, that's the time to say, 'Shall we get serious? Are you prepared to take orders?'
Removing some clothing, her choice, to give you better access, then once more tied loosely and heated some more before releasing for more stripping and more stringent binding.
Blindfold can be added early on. It is great for helping her to act unselfconsciously. It's not her any more, she's just acting a part.
And she has to write a little afterwards too. As well as you. We'll be waiting.

i would also recommend light bondage
blindfolds and some scarves for some tying up
and sometimes, just having your hands pinned is great
simple and effective, very visceral