the main strategy is to buy bitcoins and sell it for bigger price in the future
Its Trading! And trading involves risk. You might make big profit or a big loss. Whales control the market
Keep some whales within touch and ask them if its the right time to buy or sell 
But I am too excited to see the change in the price after the next halving.
And my opinion on getting rich is "think of constructive,innovative and creative ideas." . This will make you a billionaire. For instance, see snapchat. If anyone previously used such creativity and developed such application(You can always hire coders if you don't know how to code but "creativity" is what matters
), then their life would be set already 
I seem to have a couple of good ideas in mind, but the problem for me is that I don't know any coders personally... and I honestly don't trust some of the coders that are for hire on this forum either. I wish I could sit at home and learn how to code to have my own ideas come to life, but I guess I need to run into someone who shares the same ideas as me and just so happens to know how to code.
And to get back to the topic of trading, I completely agree that it is nice to know some "whales"... but in all honesty that's not a very likely scenario just to happen to know a "whale" in the world of bitcoin. I think if you were buying bitcoin right now for the purpose of trading purposes, and to wait to sell at a higher price point; I would recommend buying a couple sets of physical coins to store your hard earned bitcoin. So for one, you can sell off the amount of bitcoin that is on the coin itself... but the increase of interest and value to the physical coin itself could be a multiplier factor in terms of selling in the future.