#1. Set a budget.
Decide how much you want to spend on promoting your business via SEO. I recommend a minimum budget of $300 if you want to make a dent. (Less than that won't do much.)
#2. Go for quality links on quality websites.
This means if you're advertising your business its better to go after the higher PageRanks first, especially on websites which are on topic for your website.
Your goal should be to find ten PageRank 3 or 4 websites that are on topics directly (or closely) related to your website and get ten high quality links for $30 per link (the links will be renewed annually).
If you're looking for a website to advertise on I recommend the Lilith eZine, a general purpose online magazine with topics on everything.
#3. Pick your keywords.
Ie. If you're selling Toronto Maltese puppies then that is the keywords you want to choose. You should also use alternate variations like Maltese puppies in Toronto or Maltese dogs in Toronto. The idea is to emphasis the location and what the product is. Notice that I also used differently links for each one. This will also help to boost the SEO of the entire website and not just main page.
#4. REMEMBER to renew your ads every year. The longer the link is there the more valuable it is.