There are a number of SEO plugins on the wordpress site that aren't bad. they take care of some basic things to help your visibility without forcing you to actually know much about it.
Search engine optimization. Basically just positioning your website to appear prominently in the search engine results when people are searching for your target keywords. For instance, you might want your site to appear at the top if people are searching for "fantasy map artist" or something like that. If it's just a hobby site, then this probably isn't very important. But if it's a commercial enterprise, then you definitely want to get traffic from search engines. Assuming you target the right mix of keywords, search engine traffic tends to convert better than other marketing channels (except for referrals) because people are actively looking for what you offer.
WordPress SEO is the best one out there right now by far. Second choice would be HeadSpace2. But for those people not running WordPress, it's still good to know some basics. Since this isn't a hyper-competitive market, proper keyword research and minimal promotion will probably be enough to get you to the top.