How do I make a low-maintenance flower bed?

Since you don't say where you live and want year round color in your garden, the best thing to do is go to your local garden nursery and ask them your questions.

What I do is go to the garden center and look at what they have. Then I google my questions about it on my phone.

I agree with Shore. Your local nursery can recommend plants for your area. You also want perennials so they will come back every year. Hostas, ferns, low bushes, purple corn flowers, shasta daisies come to mind.

Flower beds, like vegetable beds, are always lower maintenance if they are raised up and separate from the rest of the yard, and established correctly. Preparation of the earth and installation of the walls is key to the bed holding its shape and remaining sturdy for long time.

Starting with a fresh load of clean soil will provide best nutrition, and eliminate the existence of any other plant or weed residue etc. that will continue to grow.

Next lay down landscaping fabric, anchoring it with pebbles or rocks so that it does not flip up in the wind. This will help prevent weeds from poking in between your flowers.

Pierce individual holes in the fabric only in the spots where you want to place your flower plants helps keep the integrity of the fabric.

Purple heart is a nice ground fill, adds color, and doesn't have to be taken up in cold weather.

Hostas are nice 1/2 the year but look horrible in the winter.

Catmint

Creeping Thyme or Phlox

Candytuft

Japanese Pachysandra is good in areas that grass doesn't want to grow and is evergreen