Fairly east to grow. Doesn't like much direct sunlight. Bright, indirect light is best. It is tolerant of some neglect in watering. To keep blooming cut off the old flowers and fertilize lightly but often.

I see you're new here, welcome. Pls. do some reading around here on mixes. While it's good that you're already using Cactus & Succulent mix (C&S for short), you will quickly see that many if not most of us here have learned to amend our C&S mixes (w/perlite or pumice, at least 30% or 50% to be safest), 'cause these days, commercial mixes have too much peat in them (kills out plants) &/or include wetting agents to retain water (also kills our plants). Others of us on here use mixes you'll see mentioned as Gritty Mix or variations of 5:1:1, things like that, which over time folks have learned worked well for them. Also some of these pre-made mixes contain fertilizer as well, which many of us wish to control ourselves rather than someone unfamiliar w/ our growing conditions. There are lots of opinions on mixes, but key & accepted by all of us is that to grow C&S, we need fast draining mix & what you've pictured above doesn't look like that. So that's an improvement that could be made easily & help the plants more that almost anything else one could try.

I wouldn't prune them at all for now. I assume yours are not overgrown after one year in place. Just take out what is dead in the spring. And be careful doing this. Some branches look dead but are not. The real white sticks are dead. Check for green centers. This is the first year some of my hydrangea macrophyllas bloomed. I bought my plants very small 4 to 5 years ago and it was worth the wait. I almost gave them all away except that I think the foliage alone is beautiful. Glad I didn't. Since you just planted yours last year, I would give your plants a little time to establish, maybe up to three years. And as Wardw said, they bloom on old wood, so the buds have to make it through the winter. I find that they break dormancy very easily so I lost most of the terminal buds to warm winter spells. A week of warm weather would cause them to start opening. Once the weather turned cold again, they would freeze. No flowers. Last winter was consistantly cold, so all worked out for most plants. If you go on the hydrangea forum, you will see some people go through a bit of trouble to overwinter their hydrangeas. Additionally, if you have a warm early spring, keep an eye on the dryness of the soil because they break dormancy early. I lost buds on one of my plants because of this once. One more. I did say they break dormancy early. That being said, as you move down the branch, it may take longer. My plants often like to put their energy into the basal buds first, sending up new branches. Unfortunately, those won't flower this year. Once this happens, it may get to breaking more buds on the old sticks and those will flower. What kind do you have? Oakleafs also form their flower buds the year before. You can see their flower buds when they go dormant. They can be damaged from the cold and die back, especially new plants. But they won't break dormancy during winter for me. Hydrangea grandiflora blooms on new wood and so does Annabelle H. arborescens so they can be pruned in the spring. The new H. mac Endless Summer is suppose to bloom on new wood. It is a break through plant. Here is a link that might be useful: overwintering hydrangea

I can't see any obvious yellow leaves in your photo, so perhaps it is just normal leaf shedding where your plant is shedding old leaves. In general, you do have to be careful not to overwater these guys. Because they have fleshier leaves, they tolerate underwatering a bit better than leafy plants. I let my potting mix dry out a little (but not as much as I would with succulents) between waterings. My Peps tell me they are thirsty when their leaves start feeling a little floppy. I've heard they'll tolerate low light, but I haven't tested that out myself. If it's not getting as much light, you'll probably have to water it less as well. I'm still a newbie to fertilizing so I'll leave that to someone with more experience to answer.