I've been boiling for, ahem, 35 years now. Ten minutes in plain water, dry with a cloth, and lay them out to dry overnight. Tried alcohol which works great but a pain to deal with. I usually get two months out of brand new set of rounds. I can boil and get maybe another month, boil again and another month. I've found that after the third boil, I usually break strings so now, after two boils, it's the trash can.
I usually buy two sets at a time and rotate them so i always have a spare in the case. I'll put a post-it note on the sleeve to remind me how many times i've boiled the sets.