Aim for a number of different flower shapes - for example daisy, bell, round or flat umbels and tubular.
A mix of perennials that flower at different times of the year will also make sure that there’s pollen across the seasons, especially early in spring and autumn when less is in flower.
Consider whether the plants are classed as native, meaning that they naturally occur in the UK - native plants are preferred. Research from the RHS has shown that having a mix of native and non-native species is likely to be the best strategy to help pollinators in gardens.