I go by this system of books-it's not mine it's from a moderator that looks into bitcoin books and rates them. "A" rated books SBObitcoin (top rated book) Anonibet
Right now for me the best decision i made was to not have money funded in bitcoin books that use actual bitcoins because of the mess the past few months, so i use the books that convert the money to there own system or cash. I use this ratings the same way i use SBR's ratings and it works fine for me and controls the risk factor for me. For D books i deposit max $500 and bet $100 a game thats it. More as u go up but i still dont go as crazy as i do with SBR's A rated books, except for SBObitcoin which its safe to say u can have any amount since it has to do with Pinnacle, SBObet.
Some of these places offer bonuses to if u want them.