The first thing you should do is find out how much your home would/could sell for to determine whether or not you're underwater. If you're not underwater, go ahead and get your home listed for sale and you should think about getting pre-approved for your new VA mortgage.
If you are underwater, you'll need to figure out how you want to proceed. Do you want to pay cash out of your pocket to make up the difference or maybe hold on to the home until the market turns around?
If you're thinking about doing a short sale, don't, you won't be eligible to buy again for a few years.
One more thing to think about. You can actually have 2 VA mortgages out at one time as long as you have enough entitlement and you qualify for both mortgage payments. This means you could potentially rent out your current home and buy a new one with your VA mortgage entitlement.
Please feel free to contact me for more information or help. You can also find info on my VA Mortgage website by clicking the link below.
Senior Mortgage Banker