PR4/5 can be achieved easily by keeping the site clean, and by getting decent quality links from relevant clean sites. Most of the free directories are just not good enough to pass on the link love. Getting limited number of quality links from othe relevant sites is what has worked for me (I wasn't aiming for PR).
Another easy but expensive way is to buy PR7/8 links and you will easily get PR5/6/7. PR of the linking page plays an important role in getting PR and is one of the significant factors - this is true only for PR purpose and may not be true while aiming for SERPs.
Need some time to handle deferred joining date by three big IT companies.
If your work is still pending, I'll soon get in touch.