How to Avoid Mistakes
The best way to avoid mistakes while collecting stamps is to collect for fun, not for profit. It may turn out to be very profitable, but you have to know what you are doing and collecting stamps is a learning process. If you realize that there is no right or wrong way to collect, then you can avoid all mistakes. That is the great aspect of stamp collecting, you can do whatever you want and it is still collecting stamps.
If you ever attend a stamp club meeting, and there are twenty people present, you will find that all twenty collect something different. Even those that collect the same country don't save the same items. For example, some only save the stamps with birds or trains on them. While others look for booklets or stamps issued in a five-year period of war, peace or transition. They can then become very knowledgeable in that topic and become an "expert" in that field. That's all it takes.
One person collected pictures of pretzels on stamps in addition to saving stamps of his own country. He was very proud to have every stamp ever issued that showed a pretzel. There were three of them in the entire world. It took him a lot of work to find those three but no one ever doubted that he had a complete collection.
There is a saying that, "Knowledge is power," and it is very true for the stamp collecting hobby. When you go to a stamp show, or visit a stamp dealer in his or her store, then you will soon realize how important knowledge is. As you look through boxes of envelopes or stock pages with stamps on them, you may find that stamp or envelope that fits exactly into your collection.
Try to avoid buying a torn or damaged stamp. Examine them closely, front and back, to look for tiny holes or tears or even thin paper on the back. This can happen when a former owner of the stamp used a hinge to affix the stamp to an album and then took it out, leaving a portion of the gum on the page. Tears happen when someone rips the stamp off an envelope and isn't very careful about the process.
There are many things that can be done with torn or damaged stamps. They can be used to cover a home made stamp album, or containers to hold stamps or for decorative purposes, but they are very rarely used as part of a collection. There are exceptions to this. If the stamp is worth a great deal of money and very hard to locate, some collectors may buy this item and put it in their album. But they will always be on the lookout for a better copy to exchange for the damaged one in their album.
It's a fun hobby and you can learn about the world while meeting new friends.