Letting them bolt!
The common thing with basil is that you have to keep picking the tops off to prevent the plant from ‘bolting’, which is going to seed. I usually follow this, but since it’s been such a cold and cloudy season, my basil hasn’t been doing so great.
Basil loves the sun, and so will stop growing large, bushy leaves when it’s cold.
I’m letting my basil plants bolt because I ran out of seeds for spring, and the leaves are too small to enjoy anyway. The seeds form very quickly so I don’t have to wait for long.