Work with some high linking page ranks sites to link to you. Hence if you have several PR7-8 homepage links pointing to you from the relevant areas then your link quality will build up to a greater level. Remember you can only jump I believe one/two max. page rank level an update. Someone here may wish to comment on this.
Having multiple high PR backlinks pointing towards your site as well as submitting articles to article directories will improve your PR and increase traffic. You should check out Angela's backlinks, they're great if you're just starting out.
Gather more backlinks from high pr sites. Join some high pr social bookmarking and social networking sites.
Get at least 2-5 PR4/PR5 quality relevant backlinks, wait 3 months or so, then you will see some PR on your site
Constant link building is the key to building PR. Content is also important for building links because this will attract traffic and improve PR altogether.