Here is a sample of PM I wrote in one of my bid. You can take hints from this. But do not copy exactly. Atleast do some change even by ms word synonyms.
Hi
I am a freelance programmer and trainer in Bangladesh for many years.
I can do all the work, you asked for:
I will do 300 post/submission at $30
I am very much familiar with Yahoo Question Answers and can do it on a daily basis, by optimizing keywords to promote your website link.
I have been doing social media marketing works for my customers for several years. So i can do it for you on a regular basis to create backlink to your website.
I know youtube terms and conditions and know how to write keyword optimized description to get search advantage.
I am familiar with online group promotion by adding new discussion, new thread, new topic and replying existing discussions to promote online business.
I do Forums Membership sites promotion on a daily basis and know how to create anchor text by bb code besides html and wiki codes.
hope you will give me an opportunity to work for you.
thanks and best regards
myakub