If you are a typical arts marketer in a typical arts organisation, or you are a one-person business, then I have to say you are being quite optimistic by expecting to be able to manage SEO on your own. I’ve never succeeded yet. This is because in this industry we have so many competing priorities and are required to be Jacks (or Jackies?) of all trades. To be truly effective, SEO needs constant maintenance and adjustment.
Don’t let that discourage you though – you can certainly manage a one-off optimisation exercise in terms of adding keywords to the primary places throughout your site and ensuring that your website’s development and functionality are not creating any barriers to being picked up by search engines. This will help you get into the top ten rankings for relevant search terms.
But it’s when you want to maintain SEO on an ongoing basis that an external SEO company really comes into play. They are watching your rankings on a near-daily basis, observing what your competitors are doing, and keeping up with the most popular search terms in your industry. As a result they are able to pro-actively suggest tweaks to content and keywords that will keep your site high in the rankings.