I understood 2 things till now.
Do not speculate as btc is volatile in case you cant afford a loss.
Buy only that much which you think can be sold and sell at the decided price which you thought at the time of buying insead of waiting for more price to rise.
Well, you misunderstood the first, and it's likely you don't understand the second as much as you think.
BTC is volatile, but so is everything else that is worth trading: it's true that you can't lose without volatility, but you couldn't win, either. Trading isn't about avoiding volatility, it's about how to capture the upside of it.
About the second point, you do capture two important ideas:
1) position sizing: don't risk more than what you're willing to lose
2) having a pre-determined exit
However, the strategy you describe is called mean-reversion and, while it may actually work, it comes with a limited upside and an unlimited downside. In human speech that means things will look quite spectacular until it suddenly won't: you'll keep winning small amounts quite regularly, and then you'll lose it all (and more) in one go. That is, unless you always set a stop-loss, but stop-losses erode the edge of mean-reversion strategies, so I doubt you could make it both working and secure. Unless you can compound very very fast, in which case maybe it'll work.
More robust are the different momentum strategies, maybe augmented with some mean-reversion to smooth out the equity curve and increase the win-ratio.