This depends on your eye-sight a bit. If you're short sighted and/or have good abilities with close focusing, it's quite easy just to see the difference - one side is the raw fibres, the other side is slightly smoother, the coating being over the top of the fibres. However, this doesn't work for everyone, so here are some other ways to work it out:

• The first is the curl - generally, coated papers will curl slightly upwards toward the coated side.
  
• If you still can't tell, there is the 'tacky test'. With a moist finger, touch both sides of the paper - the coated side should be noticeably stickier.
• The final way of telling is to do a print! Use the same image, print it on both side of the paper - you'll soon know which is the correct side (the one without the ink bleed!) and you can use this as a reference for the rest of the box!