When you start using a new coil, after priming, sitting a while, and unpowered draw, start at a low wattage and slowly work your way up until you're happy with the vape. The "recommended wattage" is about as useful as "I know I left my keys somewhere in the solar system". If a factory coil range is engraved as "30-70W" I'd start at 10 W, no vapor but that's ok. Go up a few watts at a time (without chain vaping it) and stop when you've your sweet spot. It might be 25W (which does not mean the coil is bad) or it might be 50W. It's a simple method of getting your new coil off to a nicely smooth wicking coil and getting some decent life out of it.