My secret for healthy potted plants is not to simply water the plants
where they sit, but to take each plant to the kitchen sink and give it
a good soaking (if practical). I'll stream water in the pot until
it's about to overflow, let it drain, and repeat two or three times.
This helps flush the buildup of minerals out of the soil. Peace
Lillies are especially susceptible to salt build up in the soil, which
results in the leaf tips turning brown. Since I've been watering in
this way, my plants never get that burnt tip look.

It's important to add a good fertilizer once a month during the
growing season.

As for African Violets, those you want to water from the bottom, and
don't get the leaves wet. (Most fuzzy-leafed plants don't like
getting their foliage wet.) I have mine in self-watering pots which
keep them happy. I also add African Violet liquid fertilizer every
time I add water to the pot. African Violets like to be a bit root
bound, so they'll really put on a show once the roots get a little
crowded. A north window gives them good light. Don't set them in
direct sunlight. Pinch off faded flowers.

I usually pick a day of the week, like Wednesday, to water my plants.
Most of them do fine with a weekly watering, and picking a certain day
helps me to remember to do it. Some plants you may need to water more
often, some less. You'll get into the swing of it after a short time.

Good luck with 'em.

-Fleemo