what kind of welder do you have (arc/stick, mig, tig)?
I have an old stick welder my dad gave me. He gave me a few rods and a few pointers and I have played around with it and have fixed several things around the house. The thicker the metal the hotter the heat needs to be, too hot and it will melt what you are welding.
I have built a roof rack, welded a trailer hitch on our golf cart and built a little dolly for our canoe (my first project). They are all rock solid. I wouldn't weld recovery points or anything yet but I might tack up a bumper sometime and let my dad do the heavy lifting. After awhile you kind of get the hang of setting the heat.