You can't beat worhing for yourself, you make your own hours and if you want a day off you don't have to answer to anyone. francises are genrally not a goodidea you have to follow there rules and methods which i don't think that it is then your own business. My best man brought into a francise involving car parts and stuff and it was the rules off the francise that sent him under, it was to do with the stock he had to keep instore that didn't sell in his area.
Start your own business with your own ideas by looking around your local area and seeing what is needed, no point starting something that your area already has some a few of.
You like washing YOUR car but do it 10hrs a day 5/6 days a week and see how good it is
As for partnerships they very rearly end well as one side always think they are getting ripped or over worked, i was in a partner ship with my father for 8 years before i had to buy him out or disown him.
Deversity is always a good idea, my dad would say "the more strings in a bow the better tune you can play"
What have you got to lose, still on Ps so i'm guessing you live at home with your perants so at best you will lose you car if worst happens it's alot less then if you did it in 5-10 years and were risking a house and had a wife and kids to support, the younger you are the more time you have to recover if it does not work out which is always a possiblity when starting and running your own business