For making the maximum profits all I do is set a particular amount of profit that I would need from a particular coin. Then I divide that profit, So let's assume the profit to be 10%, then 4% is what I save as fiat and 3% for investing in new coins or ICOs and the rest 3% to buy back the coin sold during a major dip just to keep the capital as it was and expanding it further by that 3%.
Now during times like the last few weeks, those 4% converted to fiat, I use them to invest in bitcoin and Other coins like Ripple, Cardano if I have those 4% enough to invest left with me.