it maybe needed investments or maybe not but lets calculate both situations and see what is most profitable..like we all know signature campaings and mining is the best option in nowdays to earn a good profit but I rather think about using some skills too ..
like I have some skills like web developing..communication skills..and so on some important skills so how much can I earn and how?
The answer to this question is... work. An attorney can make 5 BTC an hour. You'll never come near that with anything you find on the forums.
Treat Bitcoin like you do fiat -- the same ways you earn cash are how you'll earn the most BTC.