Keep an eye on you oil level as well, if it gets towards the low end of the range or even beyond that
the temp will rise.
As to mileage the best you can do is drive sensibly when in traffic (town and motorway), i.e. no hard acceleration, anticipate stops etc. and a bat out of hell when conditions warrant!
For work I almost always take the train now, the roads are too clogged and depressing to travel on for the most part, with all the cyclists, trucks, tractors, speed cameras etc.
I've tinkered around with various "hypermiling" techniques and they do make a real difference. If you can stand the boredom, try travelling on the motorway at 60mph, you'll be surprised at how much further you get on a gallon. Of course your cars coefficient of drag will means the savings vary, in my Ford Ranger they were huge, in my 911 much less so.
As a simple quick test get up to whatever speed you normally travel on the motorway and then take your foot off the accelerator (clutch in or in neutral) and see how quickly your speed drops, try lower speeds and you'll see just how much wind drag is on your car at various speeds . Better tyres will also help improve rolling resistence as well as ensuring bearings and rotors/brakes are in good condition.
I'm not advocating driving everywhere on the motorway at 60 but if the traffic is heavy and all you'll be doing is accelerating for 100yds and breaking give it a try, the petrol you save can then be used for a decent blast on some clear A/B roads (if you can find any that is).