You can only learn by looking. Nobody is forced to buy anything.
Broadly speaking collectors fall in to two groups when it comes to learning - those who gain all their knowledge from looking at eBay and other virtual sources and the second group who opt for practical experience, who do their legwork and physically examine coins. Only by comparing what is available in the flesh can you come to appreciate what consitutes a good example. Whilst a picture is said to speak a thousand words, it is also a very good way of presenting an object in the most favourable light possible, with contract and colours frequently adjusted to hide defects. You need to get a glass on coins and mentally absorb all that you see including prices and grades.