Yet another vote for Seidmans book. I have others and have literally studied them all but Seidmans was the first and still the one I turn to first. I spent an entire winter reading everything I could find in books and on the net before I ever splashed. Set the boat up in the driveway often enough that I was familiar with everything before I ever got close to the water.
I taught myself to sail...kinda. I have/had no mentor but there are lots of great folks on lots of web sites that helped me along....and I needed it. Right after my wife and I got married, 33+ years ago, we had a neighbor who would let me play with his little 10 foot. boat. I didn't learn much and did not sail again until last summer, some 30 years later. I started with a Chrysler Buccanneer....there's one for a beginner....then because it was so uncomfortable for my disabled wife moved to a Cat-22. I also came across a 1974 O'Day Widgeon for 2 bills and added it to the fleet. I use it on the little local lake and probably learn more from it than the Cat due to being able to sail it more often.
I suppose it depends on where you live and what you're used to, to some extent. I'm in the middle of the country and only sail inland lakes so navigation as regards setting a course or finding out where you are doesn't come into play. It isn't very likely I'll get lost. I don't yet sail in high winds but have reefed a few times cuz winds can be quirky here....well...I'm certain they can be everywhere. But I can heave to, head for a cove or drop sail and motor back to the harbor whereas out in the middle of a big bay, one of the Great Lakes or out in the ocean that isn't an alternative. I've learned a lot but intend on taking a course this summer so I can rent boats. I have one son in Florida and another on Lake Michigan and I'd like to be better prepared and more knowledgeable before I take on something like the Gulf or Lake Michigan. I learned very quickly that this is a lifetime learning experience, which is just one reason it is so much fun and so interesting.