I grew up on a sailboat and had some instruction from my dad, but at that time I wasn't interested in sailing. I didn't really start to "learn" until I was on my own in a dinghy. I was pretty much self taught, meaning I didn't have someone over my shoulder. I still remembered the basics and theory taught from when I was a kid. I was able to bounce questions off of my dad over the phone when I got back into sailing. I got the basics down myself but I need to work on better trim and I want to be more comfortable single handed.
As of late, I've been going out with a friend who used to race, a very good and experienced sailor, to look over my shoulder. He's willing so I'd be a fool not to use him. I learned more just one day with him than I have an entire season. Sometimes you just don't know you're doing something wrong.
I'm really glad I learned on a dinghy. Bigger boats are just so forgiving and it makes it harder to see mistakes you're making. In a dinghy, you make a mistake and you might be in the water. The feedback is instant and absolute. Also learned what stresses a rig and what doesn't since bad trim meant very tired and sore arms since I didn't have cleats.
One thing I've learned is sailing can be as easy or as difficult as you want it to be. It's easy to get the boat moving with the sail. It's difficult to squeeze just that little bit more speed out of it. Of course it can also be as relaxing or as terrorizing as anything else. Really a dynamic sport.