How can I fully prepare myself to learn piano?

I've been trying to learn piano through self-study (and practice) but I can't get used to the finger positioning. I find myself placing the wrong finger on the key I'm supposed to push very often. How can I fix this?

Also, what are some basic but very effective excercises I can do to help myself start out playing the piano better?

Thanks in advance!

Get your own piano or keyboard.