Have a good walk around your garden or even your nieghborhood. Get some inspiration with other peoples gardens. Take your dog for a walk and take some pictures of what plants you like. Make notes if there are in full sun or in shady area's.
Head down to your local nursery and get some frost resistant plants. Luckily for us here in Johannesburg we have alot of sunshine so make sure you plant in a sunny spot in the garden. Deadhead all flowers from your roses and other plants in your garden. April is a good time to also plant bulbs, consider digging up and transplanting or dividing your perennials cutback all dead vegetation.