There are so many, you might as well buy as needed, though you may pick up bargain collections at radio rallies and fleamarkets. Every now and then people on here may offer boxes of them when they're having a bit of a clear out.
Don't worry, your collection of bits will grow, and your need will swing round into identification
Everyone started out with no knowledge whatsoever. Unfortunately some people forget this and can be a bit of a pain, but I find the people on here have their feet planted firmly on planet Earth and understand how they grew their knowledge. It gives them the patience to spend the time to explain things at whatever pace someone needs. As a source of advice or learning, the only time the forum fails is when someone asks "Which xxxxxx should I buy?" and then the drown under a thousand replies, all different
David