I have a lot of squirrels around here and I have learned they do not like ground red pepper (you can spreed it around, but it can get expensive), they don't like the smell of marry-golds. I have planted a row of marry-gold around most of my garden. I have also placed branches with thorns inside parts of my garden (rose bushes might work). One can also make a liquid out of red pepper, lemon juice, garlic and some form of oil (vegetable). Don't put it directly on the soil, I use pieces of clay pots, rocks, I place on the siding where the clime down...est. You can also place species of tinfoil around on strings or how ever, when the wind blows and moves the shiny tinfoil it will help to scare them away.
PS: O ya, almost forgot, fencing helps a lot! (1in square holes is what I used)