If you are using your own dog, then I wouldn't tip......your paying for the use of the fields and the birds. If I am using their dogs/handler, then I tip the handler. As previously said, cover is important, as well as how the birds are planted. I've hunted preserves where the cover was so thick that you couldn't walk through it (nor could the dog), and cover so bare that you could see the bird sitting in the open......neither is good. I don't like corn fields, esp big cornfields......the birds can run circles around you and will flush far out if pushed too hard; I prefer sorghum or grasses. I also use a slightly heavier load, esp. this time of year.....if the birds have been fed well, they can have more fat & feathers on them then a wild bird, so I use a larger shot size (#5 or #4) and a heavier load (1 1/4 oz to 1 3/8 oz) to help penetrate those extra layers. Tighter chokes don't hurt, either....esp. if the birds flush out farther than expected. Earlier in the season, I tend to use a 1 1/8 oz load of #6 or #5 shot. You will find that, if you hunt enough preserves, you will find those that you like, those that are just so/so, and those you prefer not to use......for various reasons. I like a preserve with a mix of fields and some natural cover (creek bottoms, small woodlots), but that's just me. Best of luck, have fun, and post some photos after the hunt!