lube

Really the best thing you can do is go buy lube from the store. It's not expensive at all and you can buy it at any age. Two well known brands are KY and Astroglide, they're quite good ;-) Besides that, I'd just suggest using spit. Using soap could wear out your skin, or cause an infection (not sure if you are male or female...) however I've heard of people using shampoo before. Not sure if that is healthy for you or not, but I think it might be okay as long as you don't do it frequently.

If you use shampoo or soap, just hope to god that it doesn't go down the hole bit :P 2 days of non stop pain. (Never happened to me, happened to a mate though.)

You could use bubble bath or something, works well :P

I used patroliam jelly aka vasilen. It worked great and I had no irritation afterwards