This was my policy for a long time. To a degree I still follow it.
What I like to do now... Is keep busy in the early stages, 'box up or trash' any reminders, forbid myself any contact, and stay relatively sober to enforce that. Maybe have a little pity party or hang with a friend and 'man feeling talk' (which is 90% sitting there). Then what I do is try to fill up my all of my new free time with 'things i wanted to do' that are social... Some time and some forced social behaviour later 'getting under someone' happens as a natural side effect.
My big thing is that I want to make sure that when I'm getting under somebody I'm doing it for me, not for any reason related to the ex. Mind you, in recent years, I've had monogamous relationships, but I've been largely 'monogamy adverse'-- So I mostly 'just date' and I don't get too worked up when it doesn't work out one way or the other. (I've been in a couple of multi-year things, and a few over one year things, and at this point I'm 30ish and pretty happy to not have 'a serious relationship' as priority #1.)
It takes time and a bit of forced social behaviour. Usually, you'll know when things are right for you, but if you get stuck in a bad rut for too long don't be afraid to reach out to family and friends (or failing that a therapist or whatever). I've seen guys really fall apart after particularly bad breakups, where they really didn't have to. So if you just can't get back out there doing social things with your new free time, look for some help... Wallowing is only good up to the point where it starts to wreak your life, and sex is only good if you're having it for you.