The cynic's guide to gaining reputation:
Post well-worded answers in questions that you think are 'popsci' enough to get into the Hot network Questions list.
Wherever possible, include relevant pop-culture pictures, xkcd diagrams or lego mockups of rockets to aid in your answer.
I do not necessarily endorse the above approaches, although they overlap sufficiently with 'answering the question well' to not be an approach to be discouraged. Aiming for a well-constructed answer a day will get you a lot farther than producing many medium-quality answers per day.
Even so, a middling answer on a HNQ question can still get you quite a lot of rep.
Finally, I recommend stalking Uhoh. He asks many high quality questions, and they have an unusually good probability to become HNQ questions. It seems to be where most of my rep comes from.