If your opponent plays Nc6 without first playing c5 then the best way to take advantage is by playing d4 to stop them from playing e5. If they can't play e5 or c5 then Black will often struggle to find a plan while White's position is very easy to play. You can follow up with normal moves like 0-0, c4, Nc3 etc. If Black ever takes on c4 then you usually recover the pawn with Qa4 or Nbd2 depending on the position. Here are some opening traps that have won me many blitz/rapid games:
How do you guys like to deal with the sort of line shown below - where Black just makes standard, classical developing moves?
I do see that databases and engines tend to suggest playing, earlier, d4 or c4, which transpose (e.g. to an English or QGA/QGD/Catalan.
I also see that if you do get to the position below, results tend to favor black, and that 6.c3 or 6.Nxe5 (a theme I've seen before with the B developed to the forth (for white) or fifth (for black) rank) seem best.
What do you guys like?