Think naturally. You may be able to do this on your own with a little bit of leg work in the form of learning (sorry, not trying to persuade the OP from doing business with anyone on here). If you don't have the money to pay a professional then you need to find the time to learn yourself. If you cannot do either, you will have a hard time succeeding.
A picture is worth a thousand words! Post your high quality photos, tell a story about the picture, name your image files and alt tags along the lines of keywords (but naturally, not forcefully stuffing them with target keywords and synonyms wont hurt) and link to other internal pages. Sell yourself with the quality of the shots and the passion you have for photography within your content. Start creating tips for people who are looking to improve their skills. Again, a pretty competitive area but your knowledge and experience may vary and give you that edge.
Your pictures are going to be unique as with every photographer. Leverage your clients and business partners for links. Reach out to some local businesses and venues that you've done work with and ask if they would mind putting a link to your website in case someone is looking for a photographer.
Time, money or results? You can only pick two...
"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime." Chinese Proverb