How the inability to develop appropriate study skills may negatively impact your ability to study effectively

Procrastination, poor time management, poor note taking and not completing assignments are poor study habits that high school students need to break before they graduate.

Explanation:

in june, we will have been married for eighteen months. (i am assuming this is what you want? the sentence, as you have presented it, is grammatically incorrect--   you want it corrected, yes? )