I second all advise given so far, especially notifying folks where / when you're going. Remember to stick with your basics, Doug's basic 10 is a good start.

I would add:

Be very aware of becoming infected with "get there-itis".

It will drive you past your limits, and put you in trouble in a second.

"just one more hill, just one more hill" is good motivation for running a marathon but when you're alone in the woods and have to set up camp at the end of your hike, it's a bad idea.

Exhaustion will get you in trouble every time. You're more prone to injury and not paying attention to what's going on around you.

Leave your ego at home. It will get you into trouble every time. The forest is bigger than all of us and doesn't forgive.

Keep it simple and short to start with.

Try your stuff out in the backyard if you have one. Better to identify a problem when you can get up and go inside than in the middle of the woods where you're stuck.

I've been cold, wet, lost, and exhausted and it sucks!!!