How do you keep the plants watered without getting the floor wet?

Depending on the size of your plant containers, you can put plastic lids or saucers or plates under them.

When first putting plant into pot, lay sponges on the bottom of the pot (cover with soil...your norm. Way of doing this) this way the water will not run through onto the floor

I use plastic plant saucers or clear serving bowl from one of the "dollar" stores... The salad or punch bowls are larger and stronger... I also use a watering can with a long spout

don't over water; use a watering can with a long narrow spout; put trays under the pots, but don't let water stand in the tray -- most plants don't like 'wet feet'

I put small saucers from Dollar Store

I use old plates and saucers from dish sets that has pieces missing, also yard sales. Always very cheap.

Because we all tend to water our potted plants a tad too much I've learned to use ice cubes. The plants receive water slowly from the melting cubes and no more water on the floors! But I still use a drip tray underneath all potted plants. Best of luck!

Put a plastic saucer under the pot, available at HD, Lowe's or any garden center in small to XXL sizes.