Sloping ground can mess with your mind. I wouldn't advise changing your throw angle or pitch much because, slope or no slope, the direction of gravity is still straight down. What I mean is, say you're facing a rising slope that would require you to angle your throw up 45 degrees to remain 'flat' to the plane of the slope. Because you're throwing 45 degrees to the direction of gravity, your disc is going to stall and fall out left (RHBH). The other thing to remember is the desirable s-curve will change considerably if the disc meets the ground too soon (rising slope) or too late (dropping slope). In the case of rising slope your flight is more likely to end in the high speed right turn phase of the disc (i.e. farther to the right than you probably wanted). In the case of a dropping slope, more air time means more time for the disc to fade before reaching the ground, so it will probably end up farther to the left than you intended. When throwing upslope, it is useful to choose a 'skippy' disc with a flat beadless bottom because it is hitting ground that rises to meet it and is therefore more likely to stick an stop unless your disc likes to add skip distance.