All unlevel lies are hard–for all players.
For a right-hand golfer the ball will tend to go low and cut or fade to the right. First take more loft than normal because the ball is going to come off low. If there’s a 10′ down angle and the 8 iron has 38′ of loft–it now has 28. Next, weight on the downhill foot enough so that the spine angle is perpendicular to the slope or the shoulders are parallel with the slope. Ball position will be near the uphill foot. Feel like you are leaning down the slope. This is crucial as it puts the body in a position to do the next important thing–SWING DOWN THE SLOPE. Most Ams will want to try to help the ball in the air given the downhill slope–when they do they’ll either hit behind the ball or top it.
Take a more lofted club, aim slightly left (to account for a slight fade), set the weight on the downhill foot (how much depends on how severe the slope is–so that you get the shoulders parallel with the slope), ball positioned near the uphill foot, swing down the slope and DO NOT TRY TO HIT THE SHOT FULL. Balance is key and because you’re on an unlevel lie it’s important to swing within yourself so you maintain that balance.