PPI= #of pixels per square inch
DPI= #of dots printed per inch
A standard desktop printer 300 DPI minimum to look smooth and not pixelated :)
The higher your DPI the better quality your print will turn out.
I set print size @ 24x24 in my psd source file (=7200x7200 DPI) That way I can adjust accordingly. Hope you all have a great day :)