On this post there are two website links that will direct you to the Cancer Research UK main website which can be useful for anyone.
The first link has a good overview of why you should control your portion size both at home and whilst eating out and some useful sensible tips that you could try out:
http://info.cancerresearchuk.org/healthyliving/obesityandweight/portioncaution/
The second link (which can be clicked through to at the bottom of the above webpage) gives a very useful list of 10 top tips to control your weight and other tips / tick sheets at the bottom to help you stick to the programme:
http://info.cancerresearchuk.org/healthyliving/tentoptips/