Get your business listed on as many review sites as you can.
Claim any listings that already exist.
Make sure whatever information is there is accurate and complete.
It is easy to detect if multiple reviews come from the same computer, IP, etc.
DON’T write multiple reviews from the same computers.
They can easily detect this and they will BAN you. And they really do and there is nothing you can do to fix this.
Regularly ask happy customers to write a review.
Send out or hand out a postcard or business card with the web address of review sites where you would like them to review your site.
Do not send these links out as emails. This is detectable and the reviews are not considered “natural” reviews. They are considered to be biased and are likely to even get good real reviews kicked off the site. Really.