To make a bitcoin, you need a bitcoin.
So start with a little bit speculation. Don't fall into the trap of panic selling. Always stay calm and have patience.
My last tip would be greed. Don't be a victim to greed either. Cash in while you still can.
What you said is correct in theory, but is difficult to implement in practice.
You can convert the fiat into bitcoin first. It would be better to be paid directly with bitcoin so you do not need to convert. That would save some exchange fees.
If we are not greedy, we do not have impetus to earn money. It depends on how greedy we should be.