Do's

Concentrate your efforts on getting relevant high quality links. The more popular the site, the better rated it is (for example the higher the Google PR), the more valuable the link from it is. A good rule of thumb is that each increase in PR is an increase in magnitude of value.

People are more likely to link with you if you already have a link to them. So if youre going to ask for a reciprocal link, first create your links before you send out any of your link request emails.

Keep the links focused to your topic, or to items your visitors will be interested in. Don't just randomly link to other websites, youre your visitors and the search engines will both devalue you if you do.

The more PR you have, the easier it is to get links. I know this is a catch-22, but it's the truth. So don't expect much at first. Aim more for sites that have lower PR's and work your way up. Don't expect a website with a PR of 7-8 to link with a site of a PR2-3. Odds are it just won't happen.

Probably the #1 do, have good, unique, and relevant content thats interesting! If you dont chances are you wont get many links. Getting links to interesting sites is a whole lot easier than to boring spammy sites.

When you request a link be personable, be specific about what attracted you to that site, explain why you'd be a good linking partner, etc. In the past, I've found that I've gotten great results when I commented on a particular text from another website that got my attention. I'd spend a few sentences explaining why I found it interesting, and relate it to something on my website. It's very effective, people like when you notice them, and you're genuine. Do note that if you're faking it or if youre sending a template letter, it will produce the opposite effect.

Keep your link requests brief. People are busy and don't want to read long emails. If you send me more than one or two paragraphs, you've lost my attention. So if youre going to comment as I just suggested on the previous Do, keep it short and sweet.

Peak the persons interest. If you send someone an email with just "reciprocal link request", or something common like that, it will probably just be put on top of a pile of other link requests to get to when time permits. However if you draw the persons attention by talking about something specific, like a topic they recently wrote about, or some exciting news related to their topic, chances are much higher that you'll connect with them and get linked.

Don't be shy about putting links to other sites in your articles. I know I regularly look through my web logs to see where the traffic is coming from. Who knows who might find you? I can tell you from experience its worked for me.

Have your links page close to your home page. Don't embed it somewhere where no one can find it. I've seen this done often with the precept that itll increase your PR by not giving it away (for lack of better term). Maybe it's true, maybe not. In either case, I personally won't reciprocate with you if all you're offering is the 300th link on page 10 of your links page that is 10 clicks deep.

Donts

Don't participate in link farms and exchange programs. Most are completely irrelevant to your website and the search engines already know about them. If you're unlucky enough, you might even get your website banned from some search engines as a result.

Don't use redirects or link tricks when you offer link exchanges. Most people see through these and they quickly backfire.

Don't make your link pages look like just a large lists of web pages. No one values these links. They generate no traffic or PR for the websites listed. Rather spend the time to create a valuable links page with name, description, and some comments. It shows that you took the time to evaluate them and you really are interested.

Very important, don't send duplicate link request emails. I can't tell you how many times I've seen multiple requests within minutes from the same website. I won't go into the debate of whether or not automating link requests is good, but if you do automate it, don't make it so blatantly obvious.

Don't CC lots of people in your link request emails. This is even worse than sending multiple copies of the same request to the same website.

I understand that this is a catch-22 again, but I get many requests from people who have been blogging for 1-2 weeks, maybe 3-4. In any case, if you're the new kid on the block, don't expect links from larger sites right away. How do I know you'll be around in another month or so? Give yourself some time to build your reputation up, and then ask for higher quality links. Like I mentioned before, start smaller and build up.

Don't send emails with "warnings" that I'm in danger of losing my link from you. Firstly, they won't work, secondly they tell me you've automated the process and I'm one of lots, and lastly, odds are that your links are worthless because of their sheer quantity. Never mind that more often than not they have no relevance to my website.

When asking for links keep your link description brief and to the point. Don't try to seed your link requests with as many keywords as you can possibly squeeze into it. I cant tell you many times Ive seen linking titles that make no sense, that seem to be a dozen or more keywords randomly slapped together.

Don't capitalize your link title and/or description. The harder you make it for someone to incorporate your links, the less likely they're going to link to you.

Don't try to ask for reciprocal links by falsely saying how much traffic your site gets. It's usually pretty obvious, and if not it will be obvious within no time at all. No one likes to link to dishonest people.

All in all these are my tips. Like I said before, I've been on both sides of the fence and these are the simple Do's and Donts that really helped me.