To easily get items, take your dog for a walk and have another accessory to change into. Try to go in as many "?" boxes as possible before you go to the park. As soon as you put the line into the park, go home. Go through your walk as normal, getting items, meeting dogs, etc., until you reach the park. Once you get to the park, go directly to "Accessories". Change your dogs accessories immediately, then tap "Back". The message "Saving: Don't Turn Off Power" should appear. After it is done saving, turn off the power. Turn it back on, and you will still have all the items collected, and can go for another walk.