There are many different approaches to returning serve.
Many players like having more time so they can take a bigger swing at the ball. These players tend to stand somewhere behind the baseline. There are also players who use more of an abbreviated swing and try to get the return back to the server as quickly as possible by hitting it early. These players tend to stand on or inside the baseline at the point of contact.
There are obviously a lot of options and the server may have something to do with where you decide to position yourself on the return of serve. Don't be afraid to make adjustments, up or back, depending on your success returning serve. This will also keep the server on their toes and may force them to hit a different serve than what they usually prefer.
Another important adjustment with your position can be made by covering the wide serve (standing partially or all the way in the doubles alley) or by standing closer to the center to take away the down the middle serve. If the server is very good at getting the ball into your body, try moving a step or so to the left or right as they toss the ball. Remember to split step at the opponent's point of contact and then react to the direction of the serve.
Varying your return of serve position is a great way to keep the server off balance and also helps get you to move your feet better on the return resulting in a more solid and consistent hit.
Steve Annacone, USPTA Elite Pro, is the Director of Annacone Tennis (http://www.annaconetennis.com) and MyHamptonsPro based in Sag Harbor, NY (http://www. myhamptonspro.com) and Tennis Professional at Ventana Canyon Golf and Racquet Club in Tucson, AZ. For details on lessons, clinics, or coaching, contact Steve at firstname.lastname@example.org or call 865-300-7323