The document which was written by @RichJB is excellent for those who know someone who vapes, or who have already put their foot into the world of vaping. I didn't and hadn't - and if I had read such a document I would never have started vaping. Wattage ... ohms ... hell no, I'm not an electrician and I'm not mechanically-minded. Far too complicated for the likes of me. I think a beginner needs to start with a simple, pen-like device, where the most that needs to be done is to adjust the airflow.