Like tinsoldier says, use a long leader and cast across and slightly downwind. Don't retrieve as such, just pick up slack line as it drifts round so you keep in contact with your flies. This way your flies are drifting the same way as ny naturals out there.
Pattern wise, I go for diawl bach or cruncher on the top dropper, black buzzer on the middle dropper and a red bloodworm imitation on the point. Of course there are plenty of other colours to try, they are just my standard starting choice.
As for the best time of year, buzzers hatch all year round, even in the middle of winter. Granted, they are usually very small during the colder months but the trout will still feed on them readily. Indeed, I was fishing buzzer at Arnfield reservoir in March this year when it was so cold, my rod rings were freezing up. A bloodworm pattern took 42 rainbows including 2 doubles that day.
Give it a go, beats pulling lures anyday
Mat