Pick Guard

[Rondale]

I play a D-03.  Since there was no pick guard, I have left it as is but the pinky finger on my right hand is polishing a spot on the top of the guitar.  I want to protect the finish.  Is it a good idea to install a pick guard?  I don't want to hurt the value of my guitar nor do I want to change the tone quality.  Any ideas?

[Queequeg]

Sure, go for it.
It won't depreciate the value of the guitar (unless you do a sloppy job or put some ugly or inappropriate kind of p/g on it).
Do worry about the tonal impact either.
Lightly trace the p/g onto the top with a pencil so you know exactly where it's going to be before you glue it down. When you're happy with that, peel off the adhesive backing and lay it down.

[B0WIE]

Your pinky finger resting there changes the tone more than any pick guard ever would. That said, don't change your technique if you're comfortable.

There are clear guards if you want to keep the look of a guardless guitar. Or, if you like a little tasteful asymmetry and a more traditional look, Larrivee sells pick guards. When applying, it helps to mark your starting point with a piece of masting tape. Don't peel back all the paper on the back of the guard, just enough to get the tip in place, then you can lay down the guard and peel the paper away from underneath (attaching a piece of tape to the paper may help give you something to hold onto).

If you don't want any type of guard, applying a few layers of caranuba wax will help reduce wear directly on the finish. Just avoid waxes that may have silicones and go for straight caranuba. That's my trick for keeping contact points on plated hardware and finishes protected.

[SibeDad]

I sure wish Larrivee still sold their clear guards.  I have used them on several guitars.

[Queequeg]

I sure wish Larrivee still sold their clear guards.  I have used them on several guitars.

Clear pickguards (and pickguard material sheets) available from various sellers on the web; Stewmac and others.