Greetings, Freebooter
and welcome to the forum!
I was interested in slings a long time ago but just "never got around to it" until I found Slinging.org! Needless to say, now I sometimes kick myself that I didn't start slinging a lot sooner. I missed out on a lot of fun.
If you spend some time going through the forum you will find discussions that should answer your questions. Also, take some time to carefully read some of the how-to technical articles. In effect, you can "read the directions" for your sling.
Let me make a couple of suggestions:
Have patience with yourself. Remember that the sling is inherently a difficult instrument. You can't expect to be PONKing Canaanite giants square on the forehead on the first try. It took me about 200 throws before I started to feel comfortable with the sling and could get a consistent, repeatable throw.
I tried several techniques at first, but I eventually settled on the Apache technique as I believe it is indeed the simplest and easiest for beginners. And not just for beginners; some of the images in the historical gallery depict slingers who appear to be using this technique.
In fact, the arm swings through only about 180 degrees or only half a circle for this throw. I found that techniques that require several revolutions are indeed very difficult to coordinate and you tend to lose power and it is very odd that the sling is always shown being used this way in the movies. Check the technical articles for the Apache sling and technique.
Accuracy is difficult to achieve and requires a LOT of practice, but you can have fun long before you become accurate! Indeed, I like to
"sling for trajectory" as I call it. That is, I sling down a sandy dirt road ( lots of stones to feed my sling ) and try for good form, shot-to-shot consistency, and a nice, smooth, "elegant" trajectory. In fact, I would conjecture that slings may have often been used this way in battle. Individual accuracy would have mattered little with hundreds of slingers standing shoulder to shoulder hurling volleys ( rather like the massed musket volleys of the flintlock era. ) I estimate that I have hurled about 500 stones over a period of perhaps 4 months and only now am I trying to tighten up my groups to actually hit a specific target, but I've had an awful lot of fun getting to this point!
My sling is relatively short, only about 14 inches from release node to pouch, but I can now consistently hurl a stone about twice as far as throwing by hand.
Again, welcome to the forum, Freebooter. Read up on Slinging.org, study, practice as much as you can, and you will soon be slinging with the best of us!
.......Dan