The best way to improve social skills -- as with anything -- is practice. However, that can turn into a bit of a catch 22. In order to practice them, you'll need somebody to practice them on. Unfortunately, it's rather hard to convince somebody to become your friend by saying "Hey, can we become friends so I can practice my social skills". Chances are they'll look at you as if you came from outer space.
My suggestion is; try and convince somebody to become your friend not in words, but in deed. If you impress them with you talents, then they might be more willing to befriend you, despite your poor social skills (that's how I did it. Disclaimer: not responsible for any damages caused by attempting this approach)
But no, I don't know about any books or online courses relating to learning social skills, but I'm sure that there are plenty of YouTube videos on the subject. Perhaps look at Krystal Bella Shaw's YouTube channel? She has all kinds of videos about dyspraxia and aspergers that might be of help.
_________________
~Glflegolas, B.Sc.
The Colourblind Country Chemist & Tropical TrackerMyers-Briggs personality: The CommanderAsperger's Quiz: 79/111, both neurodiverse and neurotypical traits present. AQ score: 23 Raads-r score: here