A big question. For basic optimization ensure you at least do the following:
Put your keyword in your page title and the H1 tag (sometimes called a page header).
Ensure your body text contains the keyword a few times.
Run a free SEO site assessment tool. You can usually get one on a free trial. There are plenty of them to choose from. The better ones will highlight things you can do to better optimize your site and will give precise steps to help.
The more of a niche market you are in the easier it will be to rank in the search engines.
You will find things easier if you are a local service provider and can include your town or city in your main keywords because this substantially cuts down on the possible competition.