Hey long time reader not often i post as i feel im still in the very beginning of my share journey. As the title reads how do you know when to take some profit?

I invest in a few shares and in for the long haul but often i feel a share that im invested in sometime stagnates and then will dip and often wonder if i should have taken a slice of profit to reinvest in a dip. On the flipside i think what if it keeps going up and then i miss out on some growth so should i just leave it.

Any thoughts or advice greatly appreciated.

Cheers