I throughly enjoy talking about sailing and a lot of people (seemingly) enjoy listening. Often enough, I get the question how you get started. This is where the following post will help you.
You can get started with sailing in an infinite number of ways. The guidance many experienced sailors give is to start small and work your way up. Learning the essentials of sailing on a tiny dinghy is easier because the experience is so pure. The feedback you get from doing things right or wrong is stronger and delivered immediately. In contrast, you may have a hard time noticing inefficiencies on a bigger boat at all if you do not know what to look for. Once you figured the small boats out, you can go bigger and become a crew member, then a skipper on yachts. You will have the basics down and only need to learn some big boat specifics.
How easy it is to get started depends on your location. Regions differ strongly in the availability of sailing opportunities. Some people have the sea in front of their doorstep, others not even a lake big enough for boats within a one hour drive. So figure out where you have sailboats in your area. You might find some opportunities close by or might have to go on a vacation to learn how to sail.
The first thing that will come to mind is finding a sailing school. They will usually do a good job and there are a few with exceptional reputation. Younger aspiring sailors may however fear the cost. For this reason, it is worth checking whether there are other options in your community. Here in Germany, we have many universities that offer competent classes and boat rental at cheap prices - for students as well as non-students.
Alternatively, grab a few beers and just head out to a marina. You might meet someone looking for crew for a race or some hours on the water that may be able to teach you a great deal. Many people buy a boat hoping their wife and children will join them only to find out the partner does not like it so much after all.
My first course took three days. It taught me the practical basics of sailing and served as permission to rent dinghies there. After another extended weekend (five days), I had all the required skills to get my first license. The cost was 75 € for the basic course, 150 € for the license course and the license formalities itself were around 80 €.
As you see, you can get started with very little money.
Do not rely exclusively on books, courses or the advice of a single person to advance in the sport. Once you know the basics, go out there and gather the experience you are after to grow into your desired position. Whether it is daysailing or longer trips, start as a crew member to learn the responsibilities of different roles and after a while, try to skipper. Maybe teach some people yourself along the way. Maybe get your own boat at some point. Substitute these practical learnings with books and advice. Once you know what license is required to take the next steps, work on getting it. I will create a list of recommended resources soon.
With time, you will not only know the basics of how to sail, but also how to handle most of the common situations that may occur.
Many dinghies or small catamarans will be rented out to you without a license. Once you want to go bigger, you will most probably need one depending on the country you are in.
Things to look out for are the following: What license will allow you to operate a boat of the desired size legally in the countries/waters you want to be, will you be able to rent boats with it and will you be able to get insurance for your desired usecase.
Additionally, a radio operating license such as the Short Range Certificate (SRC) might come in handy - cell phone reception is gone faster than you think once you are out at sea.
One remark about the higher licenses: While they offer you a great deal of knowledge, there is no magic to it and you can learn these things on your own as well. Usually, the highest licenses will only be needed for commercial activities. Considering the golden days of well-paid yacht transfers are over, I would not bother with them unless you want to offer commercial trips.
That is all I have to say about where to get started. I consider this more valuable then trying to teach you how to sail in a blog article, as that will never substitute good teachers. So good luck finding yours!