Before two Days i got a project from client to rank his cleaning related keywords on google.co.uk, i am confused because i never work on particular country. I want to ask you for help share your experience what should i do to traffic and to rank my keywords on google.co.uk.

You should try to create link for your client keyword on the uk.com site.Also pay attention to the theme related site because theme related links are considered as quality link.

What you mean by theme related sites i can't understand this term because i am newbie in this field, please explain it because i am too much worried about it.

You Should
* Select the keywords after analysis the demand of your suggested keywords in UK. 

* Post your links on UK Based websites using link building techniques like
-Directory Submission
-Forum Posting
-Article marketing
-Blog commenting and posting
-Press Release
-Ad-Classified
-Social Bookmarking.. etc

* Target the traffic on UK using Google webmaster tool

You can perform off page optimization on your website

Do off page submissions in .co.uk sites, automatically keyword ranking increases in Google.co.uk.