I am currently choosing keywords for my website. I have been on many websites and peoples different opinions really make some things unclear. If anyone could give there opinion/ knowledge on these:

Which is better to use:

Keywords (eg. web, design, uk)
Phrases (eg. web design uk,) *by what I have read this is best

If I choose to use phrases, does it matter if the phrases are split up or do they have to be together?:

eg: I do web design in the uk

or does it have to be together:

eg. I do web design uk

Any advice appreciated,