Here's the simple guide to grips that works from newbies up to pros:
- Use continental for almost everything - all volleys, serves, bh slice ground stroke, and dominant hand on a 2hbh if you hit a 2hbh. There's not a lot of latitude here - just do it this way from the start. Unlike some of the ground strokes I mention below, other grips will just mess you up and then you'll have to spend a bunch of time unlearning stuff.
You can also use continental on fh slices and fh serve returns, especially if the server is pounding the ball at you. As others have said you can hit every shot with this grip if you'd like, but it will limit your ground strokes a bit.
- For a fh ground stroke the SW that you're using is fine. Anything between full E. to full W. is workable. I think some coaches start out with a more E. grip and let the player adjust to a more W. grip as they wish - I think that's a good way to go, though the SW you're currently using is a great grip.
- For a one a 1hbh use an E. backhand grip (index knuckle on bevel one). Again some variability here. Can go SW bh to continental, but like the fh I'd avoid the extremes. You might start more continent and work your way back to an more E. bh.
Yes, you switch grips on your ground strokes. You have plenty of time to do it. As Lee said, use your none hitting hand on the throat of the racquet to aid in the grip switch. That hand also is important in helping for general set-up for your strokes too.
And before someone comes after me with hatchet for stating these grips as kind of absolute, I completely understand that there is variability in grip choice among high level players. I tried to mention where the variability is (mostly in the fh and bh). You can certainly make other grips work, but you'll likely find that you'll have to change it later on if you want to improve past a certain point.