You could just start with a bike and take it apart. A lot of parts need the same special tool to remove them (there are some exceptions) but that's how I learned. Take it apart, and put it together. But since you probably want to work with newer stuff for an assembly you might be in for a lot. Start small, get a park tools chain breaker, a good set of METRIC allen wrenches, I like parks big pedal wrench (PW-4) it has 2 positions (its more expensive but its a freaking INVESTMENT that will last 50+ years). And go from there.