SEO is a massive business.
There's some good 1 hour videos on Youtube for 2016 / 2017 if you look, lots of info out there. There's no hard and fast answers, it's trial and error in some cases and don't think about using anything that says it's a fast solution, it's likely dodgy.
Without knowing the sites and what other areas you're looking at it's hard to give decent advice. Which plugin have you got for wordpress? Yoast seems to be the go to plugin for it.
The issue with photography is that it's a visual medium, that doesn't always relate well when it comes to SEO. I've not touched SEO in 6-10 months now so my knowledge is a little rusty.
Firstly, watch some youtube videos, you can spend a couple of nights doing this. Videos like
https://www.youtube.com/watch?v=y_AAO7QfsiI are decent.
Check out some of the main websites that cover SEO:
Yandex
Moz
Wordstream Blog
Google trends (keywords searches)
Google keywords
You need to have google analytics setup and running on your site. There is no point doing anything unless you know it's making a difference. Let it run for a month while you build a plan, then start changing things, seeing what that does etc.
Make sure the business is registered with google mybusiness, gets it on the google map when a search is done, also bumps up search rankings.
When searching the local area, use incognito mode or clear cache and search history as it can and does effect your results.
Look at starting a blog, 1 post a week to start, aim to use keywords such as "lovely day photographing a wedding at location name" or "I've been to the top of X hill and these are the photos I took!". Make sure all images have an alt tag as well. If someone searches for wedding photography Southhampton and you've a few photos named that they can pop up in the search results even if the page doesn't.
What type of photography do you do?
For the equestrian business, if zone 1 cms isn't up to scratch, get it moved. Get a wordpress site set up. Install Yoast etc. Get a blog going, static pages such focus on decent information over and include keywords, but don't ram them in there. It must make sense.
Seo is based on so many factors, from content, keywords, to how long a visitor stays on your site, how many pages they view etc. What questions are people going to search for and you have to consider that voice searches are increasing dramatically. "Where can I get horse riding lessons in Southampton?" Even if the business isn't actual horses/stables/lessons you can answer that question with links to local contacts with stables that offer lessons, ask them to link back to you. This is creating back links. Something that can be done on youtube, social media, other business sites, review sites. The better the website the link comes from the more value it adds to your site.
And the number one thing you have to consider is "Google's business is to provide answers to someones question, if they visit your site and leave then you've not answered it and google marks you down for it"
