My garden's tiny, so a treat some of the pots as vases, pretty much. Bulbs go in, grape hyacinths for example, when they are over they go out sight, and I move a new pot in the place. And so on.
The rest of the have herbs, pelargoniums, some annuals, tomatoes, strawberries, anything. They stay like this, I just stick more stuff when the old one looks tatty and tired. So I have to go to the garden centre pretty much all the time to see what's here.
Well just as with beds, it depends whether your pots are likely to be in the sun or the shade. You can decide whether you want architectural plants, droopy plants, bright colours or all white. You can have climbers in your pots such as sweet peas or clematis. You can have roses. You can have little lemon trees or camellias or rhodedendrons and azaleas. You can have tulips and wallflowers or lilies and dahlias or pansies and ....well anything really. As the mood and the seasons take you. Then the pots themselves can be terracotta or bright ceramic or modern aluminium buckets or old boots but they should all have a hole in the bottom for drainage. Make sure the pot is sized so as to give room and depth for the plants to grow. Put some old broken brick or crock ot stones at the bottom then some nice compost then the plant then some more compost and water generously but not too often.