Continue to deadhead flowering plants, prune back summer flowering shrubs, wisteria and some fruit trees.
As some flowers are going to seed, collect seeds from your favourites and harvest vegetables as they become ready. Some seeds can be sown now and for next spring/summer you can plant potentilla, siberian wallflower and cyclamen. You can also plant autumn and spring flowering bulbs, especially tulips, alliums, daffodils, iris and crocus.
If you have hydrangeas you can water them with hydrangea colourant and have a change next year. For pots in the house try cineraria, coleus or schizanthus.