I'd like to add a point.
Not all hill climbing is straight up the hill, turn out, and come straight back down. Practice side hilling on flat ground first. The more comfortable you are with your sled balanced on one side or the other (practice both sides), the more comfortable you will be on a hill.
I have first time riders tip their sled up on one ski to almost a 45°. The sled will almost sit in this position. This lets them know that it can hold that angle without falling over on them. Now, on flat ground, stand on one board (with both feet) and kneel into the side of the seat. Traveling about 5-10 mph, pull the sled up on the ski that is in front of you. Practice riding as far as you can on this ski. Once you have figured this out, you wil need to try it on the other ski. You will be feeling how the sled behaves so when you are on the hill and need to side hill around a tree, drift, or a hole, you won't feel that you have to have both skis on the snow. You will also be more comfortable in the sidehill position at the apex of your turnout which helps if you need to travel around the hill to a clearer run out.
Otherwise, ride loose. Don't ride with your knees or elbows locked in a full extension, you will need some movement or you can get bucked off if you hit an unseen bump or hole.