[Roadsters] Help, I'm snapping off bolt heads!

[Dave Cooke]

While removing the left front frender, I easily sheared off both bolt heads
holding the bottom of the fender near the door. It looks like I still need to
remove the doors to get to the remaining bolts holding on the fender. So,
before I break every bolt on this old car, can someone recommend the proper
way to remove old bolts? The bolts don't look rusted, but since they haven't
ever been removed, I fear I'll break off the next ten I touch with my rachet.
Also, what's the best process to remove the two broken bolts I now have?
 
Dave Cooke
69 1600
Lake In The Hills, IL