I read the many threads on Cropping and Resizing in the past few days and decided to do so with my photos so that I can get decent prints. Just want to confirm if I have done it correctly.

I am using Photoshop Illustrator and what I did was to open the photo (obviously) and using the cropping tool, I cropped my photo to the 3:2 ratio,leaving the pixels at 300dpi. The result (as per the image size dialogue box) was that my document size was 3 inch by 2 inch and resolution was 300dpi/inch. Should I leave it as 300dpi or change it to 72dpi/inch as per the clubsnap article?

I also remember reading about that the pixel dimensions should be abt 1800 by 1200, so I happily changed that which resulted in the document size to be 6 by 4). Is this step necessary? Cos I only want to print this in 4R.

Sorry if I am asking a question that is repeated many times, hope someone can help clear some of my doubts as I am not well versed in cropping and resizing.