Contacting webmasters of relevant sites requesting for have a link exchange. Write personalized emails to request for link exchange. It will be better if you write 2-3 good things about their site and tell them how link exchange will benefit both parties. Also, mentioning good qualities and PageRank is always good idea.

Do not forget to ask and give (1) URL of link, (2) Title of link, and (3) Description of Link

Now, main thing is How to find good link partner. Search google and other search engines for terms like: ?keyword reciprocal links?, ?keyword links?, ?Keyword link exchange?, ?keyword link submit?, ?Keyword link partner? etc.

I came across few tools for searching link partner:
Link Partner Finder - from 4th media.
Find Link Partners ? from zebonline

Few other tools which you may find helpful are:

Link Popularity Check - quick and easy to use web tool from Marketleap.
Arelis Link Builder - reciprocal links solution from Axandra/Voget Selbach Enterprises GmbH
Zeus Internet Robot - automatic reciprocal link generator and link directory creator from Cyber-robotics.
OptiLink Software is a link analysis program that reveals how top ranked pages achieved their search engine rankings.