55/rad offers excellent advice. +1 about having the right tools for the job. sometimes, they might not be the recommended tools for the job, but you can find out good shadetree tool info online, either on our own BF mechanics forum, sheldonbrown.com, or about a million other spots online. I look back on all of my worst mistakes and they mostly can be chalked up to impatience: not waiting til i had the right tool, rushing thru a job and temporarily misplacing small parts, not doing the smart thing with getting BB threads retapped when needed, busting aluminum chainring bolts by being too imprecise while tightening, not using a torque wrench in critical situations. Wow, i sure used to be a hack.

Good news is, you don't have to be. Sounds like you have a good helper coming to keep you at a safe pace, if you aren't patient by nature. I agree that most stuff you do wrong will be repaired, but do be careful with crossed threads/stripping threads. I haven't done too much of that, but many of the old bikes/components i pick up have at least one damaged threaded fitting. Just remember: your bicycle is a relatively simple machine; you can explore it and learn all about it, if you take the time and effort. =D

-rob

PS- remember to grease everything that needs grease, and try to use quality grease! I'm sure you've read the horror stories of stuck parts on old bikes here and elsewhere. Don't be that wrench.