Our top competitors are doing the same thing and have been for years. Besides this, three of them all have multiple sites all interlinking back and forth to each other. This kind of thin is very common and although not advised, works well for those not getting caught. It make it hard not to chase them but the risks are very high.
I stick to this and the seem to be closing in on them.
- Put keywords in onsite anchor text.
No more than 10% in keyword density. 6% to 8% seems to be doing very well.
Keywords in anchors on inbound links. Very Important.
Keywords in title and description tags.
Request links from similar sites.
Try this and see. It takes time and patients but is working for us.
Yahoo really likes this system and the pages read very well for the users.
If all else fails, Get some more inbound links - and then some more and more and more and more.
I set a goal to get 2 good links per day. If you give good links out, people will be more apt to link to you.
I get a lot of link request from sites that confine there links in a dungeon deep inside there site and hide the related link from there visitors.
Get Good link partners and always give back what you are seeking.