Hi Ave
Blimey, where to start!
In an ideal world, a business has a budget, and for the skills you don't have in-house, you outsource them. Unfortunately that doesn't reflect the reality for a lot of hobby or lifestyle businesses. But if you have time on your side, semi technically minded, have plenty of patience, then there is no reason why you can't pick plenty of stuff up.
First things first, start with the website.
Ask for some website feedback - What do you think of my Website?
Be honest, and say what your limitations are if you are the one who is responsible for the site, but it may be that some relative simple things can be addressed by some tweaking which will improve your onpage SEO.
Next thing, brush up on your SEO knowledge. How advanced are you?
I did a blog post called SEO 101 for laymen and newbies which in various formats has helped a few people over the years. If you are happy with all of these concepts and how to apply them, then you are half way there. There are also some good links to further SEO resources.
We also have an SEO education section which might help.
Likewise happy to field any specific questions if there is something in particular that is causing problems, or you want to discuss the next level such as building citations or structured data.