First what exactly are you looking for when you search for links -

1) Sites that aren't competitors.
2) Sites that look good without excessive popups / ads / etc.
3) Sites that deliver a service for visitors of your site - ie you sell baby gifts and link to a parenting advice site.
4) Sites that have a PR greater than zero - a PR of zero may mean they are in trouble with Google - beyond this don't worry much about PR - think first of #3 - a service to your readers. If it's an excellent site and they have a PR of 1 - rest assured that as word gets around their PR will climb. Conversely if their site is junk and has a PR of 9 forget them because their deeds will eventually catch up with them.
5) Make sure the sites resources page has a clearly visible link for the front page. It is better if it is a text link.
6) Review their links page - do links actually link from the site or do they use a code to link. I would be wary of linking to sites with a code because that doesn't actually deliver you any PR at all.
7) Take a moment to review some of the links from their links page - what are they like - would they provide value to your customers.

Next week we'll talk about the actual process of finding links.

Have a good one.
Tim