There is no "BAD" blowjob.

A blowjob is definitely not an activity that can be put "failed". A man may not like sex in general, and this will depend on many factors. But such that classic sex is good with the same woman, but oral sex is so-so, practically does not happen. Therefore, even if you consider yourself completely inexperienced, you can safely start practicing. Believe me, even the most banal and trivial attempts to please him will really "reach" their goal.