[wulf]

Try assessing the area you are working in. Perhaps there is a particular feature, like a doorway or tree that you want in the background. You could focus so that there is a zone of sharpness around that feature and then switch to manual focus mode so that it doesn't change - that's not good if you are walking around but ideal if you are fairly fixed.

Another option is to have a fixed idea on where you want the subject in relation to the rest of the image. You could do a series where you use the left most focus point and then purposefully capture subjects on the left hand side of the frame. Sure, you'll miss some opportunities due to the restriction but you might also find that it helps you find fresh creative ideas.

Wulf