SEO or Search Engine Optimisation is one of those areas where lots of people feel they can do this on their own. They probably can do some of it, to a point, but in order to be really successful, it is important to take on an SEO expert to manage your marketing campaign.
SEO is an area which is constantly changins and evolving; Google are almost constantly rewriting the rule book in order to keep webmasters and SEOs on their toes, so a professional SEO agency will have the know how to predict how and when Google will release potentially damaging updates.
It is important in SEO to understand which techniques are in vogue. It is also important to have an understanding of the potential risks when using certain techniques, particularly the old fashioned “black hat” techniques like mass link building and PBN use. Keyword stuffing is also a big no-no which used to be a popular technique.