Place orders ahead of time and less often do market orders.
NOTE: A general theme that shows up is about 70+% of all institutional orders are placed at prices ahead of time, while <30% are market orders.
How long to hold:
Shorter holding periods will often require a smaller stop.
Longer holding times will not require as much precision and will likely have a larger stop loss to avoid getting kicked out of minor swings to capture the underlying trend.