This group of suggestions are from Everyday Health and are well worth sharing.
Eating out poses a special challenge when calorie counting because restaurant portions are overgenerous; your best bet is to ask for a to-go box and put half your order away before you start eating.
Comment: This is one of the best ways to eat less when eating out. In the past I would ask for a to-go box at the end but end up eating most of what I ordered. With this method I cut down my amount. At first the waitress would say I'll bring you one when I bring the bill but I explained to them what I was doing and they have no problem with it. Some even say they are going to start doing this too.