I carry a small bag with 10, 12, 14mm sockets and wrenches, a flat screw driver, pair of vise grips and a flash light, can fix pretty much anything on a DSM with that kit.

I wasn't sure if my alternator was going bad or not so I used to keep a spare in the trunk.

For everything else, there is CAA My buddy, who owns a dsm also, is actually the local CAA tow truck driver.