We all start with baby steps, heck I'm still crawling... All of the little things add up. A grill block is a great place to start, it's cheap, easy and not very time consuming, depending on how complex you get... Mine took a few weeks, but if you keep it simple you could be done with yours in an hour.
A Scangauge will make a huge difference in helping you "adjust the nut behind the wheel". Changing your driving habits is probably the single best thing that you can do to increase your fuel efficiency. It's all about little changes, like going from 70mph on the highway to 60mph, turning your engine off before you shift into park, turning your car off at red lights... The list goes on.
From easiest to hardest, a few quick and easy mods you can start with (if willing) that will help you save a few extra drops are:
Max Sidewall PSI in Tires
Roof Rack Delete (if you have on)
Mud Flaps Delete
Radio Antenna Relocate
Grill Block
Smooth Wheel Covers
Warm Air Intake
Side Mirror Delete/Relocate (maybe not, if you do a lot of towing)
You can get more info on all of these mods
HERE