The first thing you want to check is your distance and balance on your feet. make sure you are not too far away and your weight is on your ankles. 

Next, check your shoulder tilt at address. If your shoulders are too flat to start you will get flat. 

In your backswing turn back so your shoulders are steeper. This will help get your arms up.

Try to watch all this in a mirror so you can see what you're feeling.

Good luck.

Stand straight up, lift your right hand and arm straight out in front of you(like shaking hands). Notice how your elbow is in front of your body, thats where you want it.

Now lift your arm up from your right side, pointing to the right, see how your elbow is out to your side, this is NOT where you want it.

Try hitting balls from a sidehill lie where the ball is below your feet - also try imagining someone standing directly behind you to the inside so in order not to hit them you have to take the club staight back and not to the inside - that will give you a more upright plane -

Good luck!

Mark F

I would go see a pro to determine if you in fact need to get rid of your flat swing.

Your posture should determine your plane (flat, upright, etc), you turn your shoulders perpendicular to your spine angle and let your arms, hands and club go along for the ride and you will be on plane and in the proper position.  Check out Tom Watson's advice on this on youtube - very helpful.  

Hope that helps,

Jason

How do you know it's too flat?  You need different inclinations for different clubs and ball positions.  If it's flat for a given ball position and club, then definitely change your swing; take the club back higher.  Before you change anything, however, first check with a video taken from down the line to see if your swingplane is flat.  Or learn to swing backwards from the followthrough to the top so as to use momentum to throw the club into the right plane, then make the backswing go to the same top position.  Good luck.

It's not necessarily a bad thing!  

I would find a TPI Certified in your area so they could assess any tightness that may be hurting your game.  The Flat swing may only be a symptom!

Check out http://www.mytpi.com

Ryan Crysler
Head Instructor
My Golf Performance Center
512.850.5721
mygolfperformance.com