Website Promotion

Looking for targeted link building on forums and posts for our website. All we want is to promote the site, services, etc, and encourage sign ups...the method of doing this we don't really mind but want to know before hand in case it is not a very ethical manner we may reject it. Blog postings, forums, social bookmarking sites, etc are all accepted..other methods are considered as well, let us know your ideas. Video promotion on YouTube is alright too..... Let me know your proposed idea and what you can deliver for the cost.....However, we don't have a large budget to work with so smaller bids are going to be considered first ...