The basis of getting into ketosis is to keep insulin low enough, and the way to do that is to keep carbohydrate intake low enough not to stimulate insulin to rise above the threshold where it starts preventing fat from leaving your fat cells.
The confusion comes from the facts that (a) everyone’s insulin threshold is different, and (b) different amounts of carbohydrate cause different levels of insulin secretion in different people. That’s why we recommend eating less than 20 g/day of carbohydrate—it’s a level at which everyone (except the most metabolically-damaged people) can get into ketosis. Your personal carbohydrate threshold may be higher than that, but start with a 20 g/day limit. Once you are fat-adapted, you can play around with the limit, but for right now, stay really low.
In some of his lectures, Gary Taubes mentions a case report he read, about an executive at Dupont, whose company physician had had great success putting executives and workers on a low-carb diet. This one executive was so insulin-resistant, however, that eating a single apple would cause him to start gaining weight. The good news is that we can usually recover at least some degree of greater insulin-sensitivity, if we remain long enough on a ketogenic diet.