Sometimes it is like turning a large ship around; SEO can be hard to turn around if the site is degraded. You need time and room to work. Most importantly you need to have a plan.
I have been working very hard for one of my clients to turn their site around. There is no budget for any SEM; so it is purely site structure and other basic SEO practices.
I began with some SEO Analysis using several free tools, some code, speed and structure reviews and some client interviews of where they would like to take it.
Here is the Google Organic results of 4 months work compared to a year ago:
Honestly it has not been easy. The site had no work done on it for over a year and had been left to degrade. Some well placed keywords, alt, title and header tags had helped. I have also implemented some structured data and fixed non-friendly links. Site speed also was a factor which I have fixed. I am pretty sure creating a proper XML site map helped the most.