Something for your photographers vest that sounds silly until you use it then you will wonder how you ever got along with out it. Fly fishermen use these. They are small little button like things that pin on the vest. they have a retractable line on it that clips onto what ever item you wan to hook to it. Gordon Hutchings hooks his viewing filter and spot meters to his. that way he doesn't lose them, or have them fall on the ground. I found my viewing loupe is a great one to hang onto the vest this way. I am forever nearly droping it. When not in use, the items can fit into one of the vest pockets.
I wopuld also second the macro lens idea. You definately will need it.
I helped a guy many years ago who had a hassy do some out door work. as fast as i was at loading backs, he was faster at taking pictures. He had 4 backs. That way if I was not around, he had several to use before he started yelling for me to find him.