On one hand drop spindle helps a lot to understand drafting and regularity, but on the other, wheel's momentum and self pulling on the bobbin will put you in a completely different world. I don't know a best way to learn, cause everyone is different, but I believe a good one is to buy a kilo of decent wool (I'd advice combed over carded if you have the choice) and spin it all in 50g batches, ply wash die experiment... That's the advise I gave to several friends and honestly I still sometimes to several 50g samples when trying a new fiber on a new wheel to get the hold of it.

Drop spindles are great though I got a couple dozen of them for very specialized uses, you can spin serving thread on some, or very coarse and chunky blanket wool on others. They allow you to work very short or tangled fibers and for luxury stuff I love it, cause there's virtually no loss at all, but let's be honest, using a hammer won't give you any hint regarding drilling a screw hole. Those are two fastening methods using the same material to do the same thing but you must learn them independently.