When you're coming to the net and you're going to hit a forehand well inside the service line, you can honestly use whatever forehand grip you feel comfortable with (I wouldn't recommend a western grip unless you regularly play on clay), but in the end you're probably going to have to end up with the continental grip for volleying and overheads anyways.
It makes your life a bit easier to use a continental grip to hit a forehand inside the service line, because when you take the net you'll already have the right grip for your volleys and overheads, but if you're more comfortable hitting with an eastern or semi western for those short balls then that's cool. Both are effective grips for the situation, but just get used to switching your grip to the continental for net play.
Originally Posted by Topspin Shot
Continental is good for slices, volleys, and some half volleys. If you want to hit topspin, use eastern or semiwestern, regardless of where you are on the court.
It's also good for hitting flat shots. But for the record you can hit topspin with a continental grip groundstroke wise. The Eastern and more Western grips are definitely better options, but with lots of practice and a strong wrist/forearm, topspin shots with a continental grip can be achieved.