Well a tip from the canal actually.
I was trying to get a photo of these flowers (whatever they are) with the bridge in the background. The problem was I had to lean out over the canal and shoot blind. I got the framing OK but missed the focus on the small flowers. The answer was to switch to manual focus, focus on the plants from where I could check they were in focus and then swing the camera out over the canal keeping the distance from the flowers approximately the same. By using a small aperture any variation was taken up by the latitude I had on the depth of field.