recommendations for fool proof annual flowers for zone 6?

Popular and common summer annuals include cosmos, cornflower, portulaca, morning glories, salvia, strawflowers and of course sunflowers. All of these should be planted where they receive full sunlight to partial shade.

Annuals that require less light and like to be grown in cooler positions and part shade include pansies, impatiens, snapdragon, pinks and coleus.

See source for more ideas.

I love impatiens because of all the blooms. Buy "Liquid Fence" it will keep rabbits, deer and all other critters from eating your flowers. You spray it all around the yard and on the flowers works great!

I don't know about deer-proof, but some annual flowers I like to plant are cornflower, nasturtium, and peony-poppy.

Cornflower is actually a weed in corn field (hence the name) so it's very easy to grow and it's blue blooms are quite pretty. Nasturtiums come in very bright colors and are also very easy to grow. They are also edible and taste something like watercress.

Peony poppies come up from seed and are pretty easy to grow. The flowers are absolutely stunning. They are technically illegal to grow in most places, but you can buy the seed at most garden centers and no one is really going to bother you about it unless you are harvesting opium.

Zinnias. It's almost impossible to mess up growing zinnias. They like full sun. For the shady areas, caladiums.