Diane Aull said
1 year, 2 months ago: How to write a link request? By hand… 
Seriously, a handwritten request sent through the mail will probably get a lot more attention than an email. Most (as in, “all”) of the email link requests I get go straight to the trash. Maybe try a handwritten post card, or an actual letter? Pick up the phone and give them a call. If they’re local, go by and visit in person. Anything so it doesn’t look like some automated mass email blast.
Let them know that you’ve taken the time to actually look at their site. Don’t just say something like, “I’ve looked over your site [fill in URL] and thought it was a great resource!” Give one or two specific examples of something you found on their site that you thought was worth the time of day.
And remember, you’re asking for a favor. You want to let the person on the other end know what’s in it for them if they grant this favor. (And please don’t let it be the tired old “we will both benefit in the search engines from exchanging links” drivel. For me, that earns any link request a quick one-way trip to the delete folder.)
So, for instance, maybe you’re a dry cleaning company and you’ve got a great article on how to remove stains from suede. You find some websites that sell blue suede shoes, or red lederhosen or vintage fringed suede hippy vests, and you suggest that a link to your article would provide useful information to their site visitors.
And for goodness’ sake, don’t threaten anybody. None of this “I’ve already added a link to you but I’ll take it down if you don’t post a link back within 10 days” stuff. If you have chosen to publish a link to something on their site, it’s OK to let them know, but make it clear you’re linking because you think their site would be of great interest to YOUR visitors, and that continuation of that link is not contingent on their linking back.
To summarize: Get their attention with something other than a mass email. Personalization is your friend. Remember that sincere compliments will get you a lot further than phony flattery. Offer something of value. Be generous.
Oh, yeah… and don’t freak out if you don’t get a huge positive response. Most people probably won’t link to you no matter what you do. Don’t take it personally; there are any number of reasons why they maybe cannot (or choose to not) link to your site that don’t have anything to do with the quality of your communication or the value your website brings to the table.
Hope this helps!