I’m currently with an American hosting company and I have the .com for my domain. I recently bought the .co.uk because I’m based in the UK, and when my portfolio site goes live, I’ll be looking to rank well in local search as well as in international search (I don’t mind having international clients as well as local clients but I want to be prominent in local searches for web design as well). So would it be best for me to use the .co.uk primarily and have the .com redirect to it?
Pick up any TLD and work hard on it, you’ll succeed. But IMO you should get two different domains for two different audiences and put all of your effort. Get links from uk domain, get uk extension, get a uk hosting company, check to see if the sites linking back are uk based as well, in WMT get your site registered for uk area and thats it.
I would use the .com and just have the .co.uk as a redirect, the fact you’re on a US host may hinder your rank locally because Google will account for the IP location.
As people in the UK will recognise .com easily, you should be able to market it to that local region (and have it appear in regional listings) without too much trouble. 
as you have both the domains…redirection will benefit you…
Use the .com if you’re marketing mulitinationally, the .co.uk will suffer in other regional googles the same way a .de or .fr would suffer in the UK search.
Thanks guys. It’s not just the UK I’m targeting, I’m also open to having international clients so I’ll use the .com and have the .co.uk point to it. I just want to be sure my site will rank well within local searches as well as globally. I’m planning on moving my site to Media Temple which I believe is based in the US as I haven’t found an UK equivalent.
If you target globally then you use .com and if you target only united kingdom then use .co.uk
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if you want to target uk market, then use .co.uk
It shouldn’t make a huge amount of difference, as long as you have both, and one is simply pointing to the other.
Using a local domain name is useful when you are trying to target local audience. And you would be almost guaranteed a proper listing and ranking in your own country if you used a local domain suffix getting your site served there itself.