Alway take projects gradually on the way up, never all or nothing.
Here is how I usually take profits:
Between 2x & 3X: take out 20 - 40 %
Between 5x & 10x: take out another 20% - 40%
If I believe the project has the potential to 50 - 100X I usually let the rest ride.
Some common catalysts are:
1. Product/Mainnet launch
2. Central Exchange Listing
3. Collaborations with other projects
If a project has been dead for several months and it doesn't have any catalysts coming, it will stay dead.