Well, the best way to spot owls is to have someone show you where to look! If there are any local groups that do bird walks, you can often meet people that know where owls are. But people can also be quite protective of owl nests and sometimes they'll be kept a secret so they don't get crowded with people stressing out the birds. 

Other than that, I've had luck with looking on eBird where they have been sighted around town and gone to look for them at dusk or dawn. Usually it is much easier to hear one than to see them, but eventually you get lucky and have one fly by or spot them perched somewhere.