When I am using a GPS for VFR navigation which is basically all the time, I do 3 things.
1) I have a SOP I follow which provides a double check to make sure that the GPS is programmed the way I think it is. The GPS will cheerfully take you completely in the wrong direction if you make a mistake programming it. Basically the last thing I do after I finish pushing the buttons is double check what waypoint it is flying towards. I then do a sanity check on the map. Not by drawing any line but just a rough estimate of distance and bearing using my eye so I can say : "Yup that looks about right"
2) I again don't bother with all the flight school bollocks of navigation by many lines on the map and filling in some elaborate form, rather I simply move my thumb along the map to keep situational awareness.
3) I pay attention to the heading I need to fly to maintain my track. This gives me and idea of what the winds are doing and if the GPS were to fail I will just keep flying that heading. I also monitor the ETE as one of the beauties of GPS is getting real time data will allow you to constantly compare how long it will take to get to the destination with how much fuel you have onboard.