With the exception of parking instructions - as discussed above, generally, just look for ANYTHING that appears to be flying roughly where ATC tells you. Then figure out what the instruction means (ie: number 2 following x, means you need to position behind it.) and follow it.
You'll quickly start to get an idea of the common types of aeroplanes flying at your airfield, and appreciate what they look like on the ground. Following this, you'll go to some farm strips and learn all other types of planes all over again! There are SO many of them - nobody knows them all! (Yes even the keenest spotter will not know some types!)