Go out and get a Garmin 96.
They will get you in and out of all sorts of trouble. Know exactly where the lat/long screen is from the main page that you actually use. This helps in wet season or when the noise goes quiet. There will come a time where you need to place a lat/long onto your WAC chart to keep yourself out of trouble. Knowing where the Lat/Longs are and exactly how to get to that GPS page is valuable in an emergency and when you have to throw out a MAYDAY in a hurry. There is no use in being uncertain of your location!
Using the MARK function is useful for plotting out airstrips and checking ALA figures. You can change the unit settings, plot the two ends of the airstrip and actually work out a decent figure for the TORA. The Nearest function will be your best friend when operating on short hops over many sectors. Also for getting references to fields that you're near for radio calls etc.
Keep an eye on your ground-speed vs TAS for when you want to fly at the most efficient level - this concept is lost on some people.
The 96 is bulletproof. It doesn't overheat and can be dropped from a decent height and still survive and is simplistic to use. They don't chew through alot of batteries and mine has paid for itself many times.
Always keep spare sets of batteries because you never know when you will be caught short.
Buy yourself a leatherman, they come in very handy.