Aces always and if you're in a decent Casino they will let you split a total of four times if Aces keep peeling, however it's hard to find a place that will let you hit any single Ace w/more than one card.
Splitting and doubling down is what it's all about, to counter the Dealer's massive advantage getting to act last
Book says surrender Eights against dealer aces ( and tens?) since you're at a slight disadvantage. And I think it's maybe just a hit when a Dealer is showing a 9.
Gambling is what caused me to relapse. Meth is everywhere once you get dialed into the local gamblers and vultures. Literally every third person has it. I once made a friendly bet with a guy who was sitting next to me at another machine (keno-- it had been a losing night). It turned out the girl on the other side of him her boyfriend smoked meth and she hooked us up and within 10 minutes we were sitting in his truck smoking. So it was actually 2-1 would have been a good wager)