I use Charts, I use Feel and I use Volume. You don't have to be perfect but you do want the stock to go to the level where you short it at. Therefore if you think that AAPL will go to $500 but maybe lower you short the $500P. If you think it will go to $505 but maybe lower you short the $505. I always pick the level I think it will go to first and then plan my spread. Therefore if I think AAPL will go to $500 that will eventually be the strike at which I short the Put. But first I will buy the long Put at $510 or $505 or $502.50 depending on which I think will give me the best return and the one I think will provide me the right risk/reward.