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.