Raising with AQo

[splashpot]

I don't know why, but this is one of the most difficult hands for me to play. I never feel confident raising this preflop. I saw this hand in a $55.

Preflop
10 handed, chip stacks almost unchanged, blinds 15/30
I get AQo in MP. Folded to me, I raise to 100. Folded to SB who calls.

Flop
47Kr
SB checks, Hero continuation bets?

I usually continuation bet here, but I seem to get check raised far more often than I would like to. What if the flop were 678? Also, is my preflop raise too small?