All my planes are tail draggers, warbirds and 3D planes. The easiest for all and absolute for some is to hold full up elevator and steer with rudder while gaining speed. Slowly release elevator when it looks like the plane has enough speed to take off. At some point the tail will rise - called rotation. When the tail is horizontal and the plane has gained enough speed it will rise off ground/grass. Feeding in up elevator at this point is similar to feeding elevator when flying a trike gear since the tail of the trike gear is already horizontal. Too much elevator will make the plane climb off steeply so go lightly.