Which side of the blade should I use?

Both sides of the blade have been pre-sharpened to ensure maximum effectiveness. Try both sides of the blade to see which side works best for you. Be sure to place your fingers about halfway up on the blade at a 85-degree angle and scrape down on the flint. Remember to add pressure. The more pressure you apply the more sparks you will produce. Note: If you are having a difficult time scraping the magnesium off or getting a good spark It could very well be you have a dull blade. In which case you would need to file down or grind the blade to get a flat edge.