Bikes are simple enough that all but the most mechanically challenged should become familiar with routine maintenance and repairs on their ride(s). You never know when something will come up on an outing and a little repair work will get you home. Some basic tools, a good manual (about $20.00) and you are in business. Caution; common sense is required.
Derailleur adjustments are the one voodoo item, but they are not that tough once you tackle it. Yes, I had a few rides with less than ideal shifting until I sorted out the adjustment sequence. But now, no fear and flawless shifting. Always. bk