I use a tarp to cover my sukkah, and have it on a slant so that the rain will slide off. It didnt work 100%, but I managed, and tried to improve it year by year.
I tie down the tarp on one side of the sukkah, and the other side (of the tarp) I use to open and close my sukkah by pulling ropes attached (to it’s edges), then I firmly tie the ropes to a nail in the sukkah wall to keep the tarp from flying away.