Student or Learner
I have doubts about when i can leave out 'a' in front of a noun:
I know the following sentence is acceptable,
"I usually give people a warning first before I punish them"
can i also say "I usually give people warning first before I punish them" ?
You can say that as well, but it only works if you habitually use old-style locutions: to give warning. But if you don't have that "literary style" all the time, it may be regarded as an error of omission.