Tampon tips?

Hey ladies! So I'm a beginner on using tampons and I just would like some tips on how to use them and avoid the TSS disease! I've had my periods for years & I've always wore pads because I prefer those but I've recently gotten tampons for pool days only so that I'm not limited in my cycle and I just need some pointers like how long they can be in for a heavy flow, what size I should stay with (I bought the "super" size), if I should keep an eye for anything unusual, and if the string the holds it in ever breaks, etc