Multiple choices...
depending on what you want the fly to be doing.
Near surface, "damp", or deeply-sunk grease-lined, you'd lead the fly with the rod tip close to the surface in order to keep the fly presented more broadside to the fish. Note: this assumes at least a portion of the line is floating.
Deeply sunk downstream traditional swing-- rod near the surface, but the rod and line upstream of the fly in all but the slowest water, to keep the fly facing upstream and traversing slowly across the current. I generally keep the rod tip for this presentation within a foot of the surface, and hold no loop of slack in hand until the fly is nearly straight downstream of my position.
Surface presentation for skated fly--rod tip anywhere from near the surface to quite high, depending on how fast you'd want the fly to skate (traverse), rod tip could lead or follow depending on how the fly was to be presented, broadside, straight down, or in between. Again, this assumes nearly all of the line/tippet poly tip are floating.
Even these "codes" could be thought of as "guidelines" to quote the Pirates of the Caribbean. All you're really trying to do is to pilot the fly at the depth, position, and attitude you desire, manipulating the rod tip and line accordingly.
Hope that is of some help.