I am an avid stamp collector. So Many different collections to choose from. 
It has been a popular hobby as long as stamps have existed.  I've been collecting since I was 6.
Have you ever tried to sell any for profit?!
Unfortunately all the stamps I have are used so not very valuable past the proof of paymeny cost. 
Are there in hard to find ones that you are still looking for to complete a collection?
I really want the Washington-Franklin issues since it was a huge change by having two silhouettes instead of the traditional singular.
How do you go about finding it? 
If I couldn't find it online I'd probably contact a university philatelist to see if they had any leads on where to find them.
Any other tips for stamp collecting you can provide?
is the study of stamps. A philatelist may, but does not have to, collect stamps. It is not uncommon for the term "philatelist" to be used to mean a stamp collector. Many casual stamp collectors accumulate stamps for sheer enjoyment and relaxation without worrying about the tiny details. The creation of a large or comprehensive collection, however, generally requires some philatelic knowledge and will usually contain areas of philatelic studies.
Postage stamps are often collected for their historical value and geographical aspects and also for the many subjects
not as if he said, "I must collect stamps so I, Paul, can obtain pleasure". Collecting stamps is not just a means toward pleasure. He simply likes collecting stamps, therefore (indirectly) acquiring pleasure.
This paradox is often reversed to illustrate that pleasure and happiness cannot be reverse-engineered. If for example you heard that collecting stamps was very pleasurable, and began a stamp collection as a means towards this happiness, it would inevitably be in vain. To achieve happiness, you must