1. Soil.
It’s always a hard time to get perfect soil.
For sure, soil must be well draining.
But if you mix with perlite/pumice which is very good but super light, the soil became very light too, so heavier succies/cactis tend to get wobbly. I usually put a thick layer of rocks at the bottom of the pot to help succies lach on to the pot and rocks so that they don’t go swimming out of their pots. Currently I’m mixing cacti soil with perlite and small amount of local soil which is very rocky, and it looks like they like it.
2. Pot.
It is good to know the name of your plant, so you can check from what country/region your succie/cacti originate, and you can choose the proper pot. Some of them like deep pots, some better like shallow.
From my experience I’m sure that clay pots are much better than plastic and it makes a big difference.
For guide to repotting read this post: http://mediterraneangarden.online/2019/01/24/guide-to-repotting-from-my-experience/
3. Watering
Another big problem for all growers.
Golden rule: it is always better to dry your plant out a little than rot it!
Most important – water only if the soil is absolutely dry.
Don’t spray with water using spray bottle, (unless during propagation), because the roots will grow up to the surface, and your plant will never root properly. The best technic is to put them in a bowl, give them a lot of water, let them soak for about 5 minutes and take them out. Of course this method works well if you have well draining soil.
And never listen when someone tells you to water once a month, or once a week or something, because all depend on where do you live, what humidity is in your area, what soil do you use and even if your plant is in a plastic or in a clay pot.