If a backlink has been added naturally by a webmaster running a site which is similar to yours in niche and subject matter, that link is really excellent.
For me,good backlink means the backlink coming from high pr sites... If the site is unindexed yet or having 0 pr value,I don't add my link into it. Nofollow or dofollow is not important for me.
This is all great information for people who are new to SEO and back linking. Where can you check for a google page rank?
What i think you need to go for do follow links as google consider them links too. Scondly try to get link from good high pr page on which max number of back links should be 20. As it is very simple that the juice of the page gona divide on number of external links..
After doing tons and tons of research I would have to agree, get links with high PR. When writing them be professional and polite and it could very well work out for you. Good luck!