The 2 lines, post flop are:
Call flop, bet turn, check river
or
Call flop, check turn, call river.
I usually opt for the 2nd one because I'm libel to put in the same number of chips each way, but the 2nd option allows the villain to bluff at me more often whereas the first one kind of requires that he has some kind of hand.
When you say usually, do you mean usually in this situation, or usually as in that's your default?
The two lines look good and it seems to me that #1 is tailor made for passive and #2 for aggressive opponents. In this case with no read, on the flop its a pretty weak bet, so I would default to #1 to make sure some money gets in the pot. If he folds, then fine, but its better, imo, than checking behind and giving a free draw. His weak flop bet and check turn is looking to fold, unless he's trapping, so why give a free chance to catch a perfect card? If he's trapping and pops us back, then fine b/c we've only put in as much as we would have called on the river, so we're not risking any more than a c/c. If we knew he was more aggressive then I could see checking behind to induce a bluff, but with a passive opponent like this seems to be I think its more likely he's c/f'ing the river anyway unless the perfect card comes off.