How do I smooth patio concrete for tile while maintaining slope?
Isn't  it a little late to be asking that question??  Get a 2x4 and run it along the framing for the concrete, smoothing it out.

Even if the concrete isn't totally smooth, when you install the tile you can smooth the rough surface of the concrete with the mortar... If the slab you poured has the proper slope make sure each tile is flush with the slab and you'll get the slope you desire. Good luck