Adding keywords to your metatags is a waste of time. The most important place to get your relevant key words in is the title and h1 and h2 tags.
SEO is not rocket science but it does take time and experience to do well. The basics are pretty simple but if you're in a competitive market it can really get tricky.
Also I always advise against hiring anyone who guarantees results. There are some really good companies out there but they do not come cheap.