I had the same problem and two things have helped me. First I changed my 1/4 inch foot. It turns out there are two different kinds, one with the little piece of metal hanging down so you can line it up with your fabric and one without. Surprisingly enough, the one without works way better for me. Second, my machine allows me to move my needle slightly to the right or left. If I move it slightly to the right, a scant 1/4 inch, I end up with a 1/4 inch.
To be honest, I don't think the way I press helps any. I am working on that too.
Like DebraK says, keep trying things. Something will click for you.
Dina