To print coupons you obviously need a computer and a printer. Please note: coupons do not need to be printed in color!! Even if you have a color printer, it would be advantageous for you to change your printer options to print your coupons only in black and white. Often, your coupon will print with a large advertisement under it. What a waste of ink!
If you don't currently have a printer, I would suggest purchasing an inexpensive laser printer. I have a Brother laser printer that I got for $50 at one of the office supply stores. It prints great, and the toner seems to last and last. Also, the toner ink doesn't dry out like in inkjet printers.
Also, consider the fact that some stores will offer a credit if you trade in an old printer. And it doesn't have to work, either! So if your current printer breaks, hang on to it in the closet - it could be worth a nice discount for you in the future.