1. Be a user first, link developer second. If your link is not going to provide value, why bother? Think like a user and make sure that the link makes sense before you post it or submit it.

2. Keep hunting for the contact info. If all you’re finding is the webmaster@domain.com email, keep hunting. Check the site map, About page, staff page, etc. until you find an actual person to contact.

3. Check more than the PageRank. PageRank is good, don’t get me wrong, but it’s not the end all – be all of a site’s value. It’s a snapshot. Check who’s linking to them, how many pages are being indexed in both Yahoo and Google (major discrepancies here can send up a red flag), and the overall quality of the site.

4. Check partner sites. Even if the site that you want doesn’t take links or turns you down, find out who else is linking to them or has links on their site. If the relevancy and quality factors are there, send the email.

5. Evaluate who is linking to the competition. While some link developers say you shouldn’t do this because you’re always chasing the competition’s coat tails, I disagree. If the competition is on a page, why should users only have that option? They should have the option to choose the site you’re working on.

6. Let randomness take over. I tend to have a bit of ADD, which actually helps in my line of work. I roam the net, clicking what interests me and let the user in me take charge (yes, this relates back to #1). Chances are other users will surf in a similar fashion. I keep track of all the pages that I find that may work for a link request.

7. Use Google blog search. Or other social media monitoring tools. If people are talking about the site you’re evaluating, that’s a good sign. But make sure it’s not all negative. A mix of both positive and negative comments and posts regarding these sites make it legit to request a link from them.

8. Document everything. Inevitably, you’ll find yourself at a point where you’re wondering “where did I see that information…” and it will be lost. Be sure to document any pages you stumble across that may be helpful in later work.

Thanks for the advices!I'm a beginner in research,so this informations will help me!