You can increase PR scores of your two blogs through gathering some links which come from high PR web pages and with only a few outgoing links but why are you interested in boosting your PageRank values of your sites? The main issue today is trying to figure out how traffic shares and organic web placements of websites can get enhanced rather than affecting the PR numbers which although being significant, are not enough to push ranks of domains on pages of Google in an upward direction.
If you search the net, even in your own targeted niche, you will be able to find some low PR sites and blogs which tend to have better ranks and stronger positions than their high PR competitors because they could have better links, coming from relevant sources and at the same time containing valuable contents and informative articles which are accessed and studied by a lot of people on a daily basis. PR is one factor considered by Google and your sites can have top ranks with low PR scores.