Step 1: Location
First a note on locating the shelter for the most accurate readings: The National Weather Service (NWS) advises that your sheltered thermometer should be
-between 4' to 6' above fairly level ground
-which is typical for your area (sand with a little grass here),
-has good cross-ventilation,
-and which is located 100' or more from concrete or asphalt paving
-and at a distance from the nearest building equal to four times the height of the building. As my house is about 12 feet high, I needed to put the post about 50' from the house. The advertised range for my thermometer is 100', but if you've got a cheap thermometer as I do, I would leave a wide margin for error (i.e. no more than 60' or so).
Now if you live on a small lot in town, you are looking at this and thinking "no way!" This is true if you want to supply data to the NWS. On the other hand, if you just want to know what the temperature is, say, out in your garden, put your shelter there and don't worry too much about it.