Isn't one of the ways check Coinmarketcap and then check which went up the most the last week or day? Of course if you do that... well many coins probably already hit the peak or close to it?
If you do it that way most of the time you gonna just find a coin that's already past its bullrun phase, but even if you found one that's still on the way to its peak you gonna be really hesitant since it's already going up and it might go down anytime. The best way to discover coin that's gonna get bullrun is the news regarding the projects.
Correct, that will let you find coins that already went through a significant growth and that for the most part will not keep growing, the only way will be to monitor the market and buy a coin that is just growing slightly and that has good fundamentals and hope that you are in when a bull run happens, this is less risky but the chances you will be invested in the right coin at the right time are small which is why this strategy will not have a high probabilities of giving you success but when it does it could offset all your losses and give you profits as well.