HU, small blind completes

[bismillahno]

I recently pulled a horrible beat on my heads up opponent when he completed his small blind, and I had 83o. I hit a 3 on the flop, and pushed, as I had read him as weak tight (comments on whether this is too aggresive?). He called flipped over aces, and must have been cursing when I rivered an 8, and went on to win. But it got me thinking about how to play against opponents who do try and limp, rather than coming in for a raise.

In my (very limited) experience, players at 10+1 will often try and see a flop cheaply on speculative hands by just completing. I've been playing the BB similarly to the SB from this case, betting (or pushing, depending on stack size/BB) with roughly the top 30% hands, and checking with the rest.

However, should I be more cautious than this, particularly if the opponent seems to be mostly opening with a raise?

And on the other side, inspired from one of Strassa's hand histories, I've been betting from SB even with my monsters heads up, as it would seem too obvious I'm slowplaying something. Am I giving my opponents too much credit at this level? Advice greatly appreciated.