I own 2 Fluke multimeters (auto technician by trade) and they are worth the money. I don't even use my resistance tester anymore because all my builds read about +/- 0.0x off. I sub ohm all the time, from the time I wake to the time I go to sleep. The build I am using now is 0.18 Ohm twisted 24g dual coil. While it may not seem like much a few hundredths (at this level) make the difference on my VTC4's being safe and being unsafe. Never take anything for face value when you're potentially putting yourself at risk. Double check everything, and you will have the peace of mind to enjoy it.
Also, do not take a warning as a fluke. If something starts to get hot (switch, tube, anything that doesn't normally) then stop and recheck. Make sure you're contacts are clean, make sure they are getting a solid connection. Any scorched spots on your battery or contacts or tube indicate you are doing something wrong. I had this happen to me once, my switch was getting warm after a 2-3 second pull. I took it all apart, and my bottom contact wasn't adjusted properly because I had built my new build in a different RDA and did not adjust the contact pins to accommodate the slightly shorter 510 connector.
Never take anything for granted, get in the routine of double checking everything when you change anything. Be conscious of the fact that what you're doing probably won't kill you, but it will hurt, bad.