1. A bird feeder should be placed at least 7-8 feet from any structure and be placed on a pole 5 feet or higher.
   Metal poles are probably best because they are hard to grab onto and will cause the squirrel to slide, when they try to climb it.
   Wooden poles are easy for squirrels to latch onto so are not a good deterrent to use.
   
2. There are three basic baffle types.
   Locating a baffle above and/or below a bird feeder can frustrate a squirrel that's trying to get to the bird seed.
   There are dome hanging baffles, wrap around baffles, and torpedo baffles.
   All types of baffles create a barrier between the seed and the squirrel; however placement for each baffle differs.
   The wrap around baffle can be placed above or below the feeder, the torpedo baffle is must be placed on a pole below feeder, the dome hanging baffle mounts above the feeder and should be at least a third bigger then feeder or it just becomes a slide for the squirrels.
   The dome hanging baffle also offers weather protection to the bird feeder.
   
3. Use a squirrel proof feeder.
   The squirrel proof feeder uses a cage with openings designed to be only large enough for bird to fit through.
   Some feeders have a weight mechanism attached to close when the weight of a squirrel is detected.
   
4. Shake Away or Bobbex are good squirrel repellents that use hot and spicy natural ingredients like cayenne and chili peppers to drive squirrels away.
   With using repellents it is sometimes necessary to reapply after rain or a certain amount of time, so read the directions carefully.
   
5. Bird seed can also be a deterrent for squirrels.
   Cardinals, chickadees, mourning doves and finches like to eat bird seed with safflower in it.
   The squirrels do not particularly like to eat safflower seed.
   Feeders filled with black oil sunflower seed will draw the attention of a hungry squirrel.
   

If after everything you tried and you still are having trouble with the squirrels in your backyard do the old "if you can't beat them join them" trick.
Add a squirrel feeder to your backyard.
They can be distracted with their own feeders filled with nuts, corn and seed, which should reduce them from raiding your bird feeders filled with the higher, priced seed.
There are many styles of commercially available squirrel feeders, most designed to hold ears of corn - a favorite of squirrels and chipmunks.