SEO to improve my rankings

I need to get my website to rank further up Google UK. It is not listed in the top 10 pages of google.co.uk. My site is not optimised for specific keywords and the keywords and the website may need to be re written slightly to help the SEO. It has been designed by a company in the North West through Wordpress and I am happy with the layout and design. I have Twitter feed which I have been told does help with SEO. I could do with advice on how to best use this to attract customers.

I need some who has a track record of successfully helping other companies with examples of previous work.

We are not a large company just two freelancers that work from a home office and provide our services on a B2B basis for UK companies.