A few years ago, I came back from a 4 day work trip to many dead houseplants. This time around, I now have 3 dozen of many different varieties. They're all happy, partly because I choose no longer to raise ferns. If you ever get complacent, just get yourself ferns. RIP your self confidence.
You are loving your houseplants too much. If the plant is browning at the tips, you are giving it too much water. The veins are bursting and the leaves are rotting. This is what is causing the discoloration at the tips. We are taught to think yellow or brown means under watering. This is the most common incorrect mental model.
If the soil smells moldy, that's another sign you are over watering. The roots of your plant are rotting. You may not be able to see it, but a similar effect is happening to the roots where the tips are decaying. Basically, we keep killing our plants softly.
For succulents, the leaves will fall off if you gently touch them. They don't brown at the tips since they are designed to save up water between droughts, so it makes sense they are too full to sustain themselves when over watered.
There may be a chance your over watered plant is beyond saving. It's happened to me too, several times. Thank it and give it a proper burial in the compost bin.
All indoor plants are already getting lower light compared to being at a nursery. All plants need to be next to a window or skylight where they can "see the sun." Ideally, this window will face the east or west for low light plants and the north or south for sunlight loving plants.
Your plant is happy when the leaves are green or the variegated color they are supposed to be. Your plant is happy when it's making new leaves for you at the rate it loses old leaves or faster. When an old leaf dies off, it will yellow evenly across the leaf. Remember, when it's over watered it will brown at the tips.
Some houseplants will bloom at peak contentedness. It is truly a joy to reach that point.
It has probably never been unless you've literally ignored the plant since you've had it. During my most recent move, they packed a succulent into a box where it sat in storage and transit for 3 weeks. It was still alive when I got it back!
Buy well draining indoor plant soil. Before you use it, make sure there are no bugs in it already. Before, I used a soil mixture from a book, How Not to Kill Your Houseplants. Honestly, I'm past my experimentation phase, so now I can attest that proper care with even basic tools will suffice.
Having a soil meter may be helpful when starting out. It measures light, soil wetness, and pH. Sometimes an insect invasion is hard to avoid. Make sure to have gnat strips and hydrogen peroxide on hand. You use a 1:4 ratio with water solution to kill the bug eggs. Water after normal watering to mitigate root burn.
I recommend philodendrons such as monstera or marble queens, snake plants, zz plants, the pilea, and hoyas. Really truly succulents are easy to keep alive so long as you don't overwater them. Remember their natural environments are very hot and dry.❀