Pick them up by hand is about the only way to get them all. Either after piling with a rake or just gather them as they sit, you will be doing some hand work.
Problem with a rake is that they tend to gather a lot of dirt along with the sticks so then you have to sort thru the pile of dirt.
If you have a tooth bar, you can lightly drag the teeth in the dirt with the bucket full tilt, but go slow incase you hit an immovable object, to gather them into small piles. The toothbar will allow most dirt to sift thru while gathering most of the sticks, a few will sift thru though and still require some stooping and bending to hand gather.
The good thing is that the small ones will rot fairly quickly and the tiller will chop most of them even smaller.