Ways to improve PageRank

You can start by submitting your website to the Top Directories, especially those who are related to your product or industry. This includes exclusive, membership directories as well

Study your competitor; see who links into their site. Get your clients, sub contractors and partners to link their websites into your site.

Do not get involved in Free for All links, even though they advertise themselves as a popular means of link building, stay away from them if you want to avoid spam. On this note, stay away from building farms too. They exist solely for the purpose of increasing their own link popularity and will most likely consist of links which are not related to your site.