A good way to get incoming links is to find good "dead" sites in your niche i.e. sites that used to cover the topic quite well, but which are now clearly gone. Then you can look at who links to those sites, and contact the sub-set of the linking sites that seem to be reasonably regularly/recently updated. Let them know they've got a broken link, then very gently suggest that your own site might make a suitable alternative.
4 caveats:
1) Don't harrass them - 1 email is plenty; if they do it, they do it. If they don't, they don't.
2) You have to be honest with yourself: is your site really a decent enough substitute for the dead site for what you're suggesting to come across as credible? If not, improve your site (but don't waste other people's time until it's GOOD). If you can't be bothered to put the effort in, then forget the whole thing!
3) If there are a LOT of sites that link to the dead site, then try and stagger your requests. Google still seems to like steady link growth, so it's not too helpful getting dozens of links over a few days, then none.
4) The dead site has to be clearly irrevokably dead. If it doesn't resolve that's not good enough, because the server might just be down. But if it's resolving to a parking page or something completely irrelevant, then it's a candidate!
BTW, an even better variant on the above is if you can track down several dead sites in the same niche. Then you have more ammo to go after. And if you can find sites that are A) currently updatedish and B) link to 2+ dead sites off a single page, then they're super-duper-good targets for the above approach.
And yes, it is work with a capital "W". But it's a tactic that's worked for well over a decade, so there's no particular reason it should fail now.
