Always check rating of the company and read carefully all cases, either succesfully closed or those which are unsuccesful.
Share your opinions about so-called 'fair use policy' used by internet providers. Make a comments on what concerns you with regards to it.
By writing your review you not only try to stop mistakes and bad attitude towards customers but also you raise your voice on the future of reviewed company.
Make a funny comments about the operating system you use and in what shape your computer infrastructure is.
Point out difficulties you might have experienced while using online services like internet shops, nuisance emails, spamming websites, malicious software.
How to make your case more succesful? Whilst posting a review choose 'response required' option and add a customer service email. What happens next is we send your case to them with no details of yours so the response will be available on our website.
Review night clubs you have or have not had a good time in. Post a comment on good food spots, restaurants, cafes, etc.
Share your customer reviews with others to promote good and reliable companies and discard those who should not be on the market.
Find more about a company you are planing to buy from or use for services and spend some moments on reading before making up your mind.
Allow your complaint or compliment to be widely visible to other customers and remember it all helps to make a right decision on whom to choose to deal with.