Creating a Watermark and Cropping

timparker_NikonD60

I am new to all of this, I just recently bought myself a Nikon D60. I am starting to get some of my shots printed out. I have some that I am thinking of giving out as gifts/etc and for possible use in a couple businesses as random wall art. I would like to put something small on the picture.

This becomes kind of a two-fold question, so far, I have just been taking my files to a local store and using the photo kiosk to get the prints done. I can naturally crop and edit the files right there. Is this the best process?

I have Corel Photo Shop Pro Photo X2 that I can crop and add a watermark with, but I don't want to end up with pictures that are out of proportion or anything.

Any best practices here? I have been attempting to search and read as much as I can as I shoot and learn! Crop at home? Crop at a kiosk?

TIA.

Tim