Impress your grandparents when you make them birthday cards by making words that are bold enough for them to see with out their glasses. First, draw block letters with a bit of extra space between them. Then decide what direction the 3-D edge will be facing and on each corner of the letter make short lines all in the same angle as seen below.
Then connect those short lines and your letters are now 3 dimensional!
Make sure all the lines are going the same direction and on the same side of the letter or else you end up with weird, crazy diamond-y letters. Enjoy!