Hydrangea bushes can be pruned now. I cut the dead flower heads back to the first pair of strong plump buds closest to the old flower head. Weak, straggly stems are taken out at the base, and I also remove completely a couple of very old gnarled woody stems each year. Lacecap varieties are pruned more lightly, cutting back to the second pair of leaves below the old flower heads. You can use some of the pruned pieces for hardwood cuttings. If you want to change the colour of your Hydrangea, you can start to add aluminium sulphate to the soil around those you wish to have blue flowers, or lime if you want pink flowers. I have never done this.
If I had roses or deciduous fruit trees, I would prune them this month. Citrus trees can also have old wood removed now. Fuchsia can be pruned, cutting back by about half. Young plants should only be pruned lightly. Kniphofia plants can be cut to the ground after flowering. The leaves are valued by weavers to make into baskets!
Trees can be shaped at this time. Some large shrubs - such as Camellia, Photinia and Viburnum - lend themselves to being formed into small trees by removing lower branches and thinning and shaping the canopy. This gives space below for planting smaller perennials and groundcovers.
I still think it is best not to prune warm-climate plants now, as they prefer to be done in mid-August or even September in some cases, and will be more prone to frost-damage if cut back too soon. Also, don't prune spring-flowering deciduous shrubs such as Deutzia and Weigela, as you will be cutting off the flowering wood!