What Should We Need To Follow As A Linkbuilder?

i work as a SEO consultant science 2008.First time i face a problem and that is one of my clients want high PR backlink .Here high PR means actual PR.
As per i know that only blog comment can provide actual high PR backlink .Look for automated blog commenting software ,every webmaster get thousand of comment each day which are automated.As a webmaster i dont like this type of comment and i think others are also same.I always delete all comments without reading and i think others are do same think.That means it is always difficult to approved blog comment.And also when someone work for others means he/she need to send theme weekly or monthly report.and he/she need to show the approved backlink and thats why i always dislike blog commenting.I know few blogs are auto approved with High PR.But this type of site has high OBL and i think Google dont like this type of backlink.
normally i like to do social bookmarking and though my bookmarked social bookmarking site has PR but you know newly create bookmarked page has not any PR and thats why my client is seriously concerned and may be he is not like this.
and i think newly created backlink like social bookmarking,forum posting,forum profile,directory submission,article directory,web 2.0 properties ,wiki link is not provide high PR accept blog comment.
what can i do for this issue?
What i look ?domain authority or page authority?
Please give me serious answer..............................expect all seo consultant and also seo service provider give me perfect answer for this issue to solve my problem.