I've started to host at my place STT on a weekly basis. Could anyone recommend on any studying source? Specific website/ YouTube video which teaches STT strategy and learn how to play better?
Second - you must to know - there are no modern good materials now. Nothing at all. BUT:
If u totally newbie:
BOOKS
Sit 'n Go Strategy Paperback by Collin Moshman (2007). Here u will learn basic things, SNGs structure, ICM, basic techniques (steal, resteal, stop-n-go, openpush etc).
Crushing Online Sit and Go's Paperback by Greg Jones (2013)
Here you will find some stuff like HUDs using and program soft. After that some PUSH/FOLD/CALL charts. Not good for nowadays (Greg use SNG wizzard for this. It was good in 2010, but not now), but still nice for start. HeadsUp part is very useful too.
Kill Everyone: Advanced Strategies for No-Limit Hold 'em Poker Tournaments and Sit-n-Go's (2009) - I have not read this book, but a lot of good reviews about it. And i heard that EPT commentators advised to read it even now
Here we have a trick - SNG is pretty much like MTT. Much faster, but same idea. So you can find and read some tournament books and articles. My favorite is Miikka Anttonen this "The Ultimate Guide to Big Blind Defense" and "Complete Guide to Tournament C-Betting Strategy".
Programs
Trackers - Poker tracker or holdem manager.
For modern Push/Fold stuff use ICMizer2, holdem resource calculator or simple nash (last is free).
For post-flop game - Flopzilla, GTO+
Video
!!!!!!!!!!!Don't use TWITCH for learn!!!!!!!!!!!! It's more about funny stuff, but not educational content.
There are no video courses on SNG's. Or I could not find them.
I saw a course for 6-max hyper turbo SNG's but i like 9-max now, so can't say anything about 6-max.
At youtube you can find some old videos (2014 year or same) on PartTimePoker channel. After that try to find some video training sessions. It can be helpful.
and for sure
"The Mental Game of Poker: Proven Strategies for Improving Tilt Control, Confidence, Motivation, Coping with Variance, and More"
Poker = Pain. So mental stability is a key for success.