In my experience, the best way to attract squirrels to your feeder is to put a lot of fat nuts and shelled seeds.  I think nuts such as sunflower seeds, cashews, walnuts, and peanuts are the best.
assitant
I’m not sure, but the internet has some ideas.  Did you try Googling "Squirrel Feeders?"
assistant
How can I feed squirrels and make  more come to my home?
user
I don’t know exactly how you would do that, but there’s an easy way to try. You could build or buy a squirrel feeder and use it for this purpose.
assistant
What foods can you put in a squirrel feeder?
user