Coming up with a new idea that you didn't see somewhere else is very satisfying, even if you later find that someone else got there first.
Over the years I have discovered loads of new tricks. As far as I can recall I have only ever used a handful of methods.
By far the easiest way of coming up with a new trick is to take an existing trick & take it a step further. Add an extra flourish, carry the prop somewhere different, can you throw & catch the prop in some way where the prop would usually just be held in the hand?
Mills Mess is often considered an original pattern, however Steve Mills who is commonly regarded as the 'inventor' of Mills Mess has said that all he did was work out a symmetrical version of an assymetric pattern shown to him by a friend. That pattern was the Half Mess, which is merely a combination of Over the top & Under the arm throws.
Many of the tricks that I discovered were also extensions of already existing ideas. For Relf's Revenge I simply added an orbit to The Follow, for Relf's Rubensteins I just combined my revenge with Rick's.
This method is unlikely to help you come up with anything really ground breaking though.
A better method is to ask yourself, "What have I never seen before?" then learn it.
A similar method is to put down your props & close your eyes. Now move your arms or any other part of your body into a position you have never felt while juggling then find ways to juggle into & out of that position.
What's in a name?
In my first couple of years as a juggler I named all of my discoveries after myself. Partly due to vanity partly to annoy Dave L.
In later years though I have taken my lead from Hari Seldon (again something else that wasn't my original idea). Instead of naming them after myself I have taken to giving them descriptive titles. It is easier for jugglers to discuss tricks if the names used describe the trick in question, rather than requiring specialised knowledge of some cryptic name. Unless you are a celebrity performer who is famous enough to have your image associated with your trick then it is unlikely to become a 'must-have' trick.