I looked into jousting a few years ago. Then I sobered up. :) It's easy enough to get hurt without someone charging you with a lance.
There are several different types of jousting.
One is just riding with a lance and picking up rings. This is about as safe as it gets.
Then there is theatrical jousting, like you see at RenFaires or "Medieval Times." This is all staged. For anyone who doesn't know, watch the riders feet. Before the run where someone gets unhorsed, the rider to fall will take his feet out of the stirrups. These people are doing this as a paid gig - they have no intention of getting hurt and losing time at work.
Then there are the two schools of competition jousting. There is the European association(s) and the American (i.e Full Metal Jousting) side.
From what I have read, the European version is a bit more civilized. They attempt to have some safety built into the sport.
The American version (one of the top riders is on Full Metal Jousting) is apparently much more dangerous. From what I read, there are major injuries at virtually every match. Riders continue to compete with broken bones... it seems like a gladiator type sport.
If that's your thing, go for it. I have broken enough bones and don't need to break any more.
Medieval stuff is cool and can be lots of fun. You do have to be very careful with things like jousting. Full contact competition can be extremely dangerous. Better to stick with jousting for rings or at least use "nerd" lances if jousting against someone else.
If going for full contact jousting, my only suggestions are 1) learn how to fall (while wearing 100lbs of armor) and 2) have a good orthopedic surgeon on speed-dial and make sure your medical insurance is up to date.