Well unfortunately this isn't an easy question to answer. I have a lot of confidence in my opinions about the market because I learned it doesn't serve you well to doubt every decision you make, so I just act on what I see as true. That's what I encourage most others to do too, but it's easier said than done. Some general ideas though:
- Move altcoins into Bitcoin when dominance is low (check coinmarketcap.com)
- Sell Bitcoin when it has big pumps (days where it is up 15%+)
- Increase cash position when you feel market is either frothy or has high probability of going down
The issue with this advice is you need to have some idea of what you think is going to happen next, which can be difficult to do without becoming emotional. Not too much that can help with that other than experience.