when a try to hit a D chord? or any other for that matter. i am just starting( this week) and it kills me when i cant keep my fingers off a i got fairly big meathooks.
Practice, practice, practice. Eventually you'll get better.
When life gives you lemons, squirt juice in your enemies' eyes.
yep thats it.the tips of my fingers are kind of fat.granted i just started trying to play
It really is just keep practicing until you can strum them cleanly. If you find your fingers catch other strings just keep strumming slowly up and down and move them about a bit until they don't. Try to put your fingertips straight down onto the strings as this makes it easier not to hit other strings. Also make sure the longest part of your finger tip is in line with the strings, if your finger tips are at an angle to the strings then it is more likely you will catch one you don't want.

After alot of practice you will be able to do it no problem and find a playing style that is comfortable for you. The first three months of learning to play the guitar tend to be the toughest but stick with it and after three months you will start to rapidly learn things.

Good luck

Practice. And ensure that your thumb does not creep too far up the neck. The further up the neck your thumb goes the harder it is to arch the fingers.