From my own experiences, you should divide your capitals into 3 parts, one for long-term investment into a crypto that has a clear and bright future; another for surfing; and the last one as backup money for an unexpected situation. For example, you have spent all the money surfing, and suddenly the next day red is all over the Exchange. At times like that, you can use the backup money to continue to surf. For my case, I bought XRP at the price of 11500 Sato thinking it has already at the bottom. But the next day, it continues to fall to 9400 and thanks to my backup plan, I still have some money to buy. This plan has saved me many times or at least help to reduce the losses. Anyway, these are just my experiences in Coin trading and I cannot ensure things will be the same for you. After all, this is just a small rock from that mountain you are about to climb.
I will not buy all at once instead divide my investment money into few parts and buy in small quantities on a regular basis so I will get a better price over the time.
Yes, we can't predict the future so many times we experience that after we sell any coins next day that particular coin will be at the moon or after we purchase certain coin then next day it will be dumped. So I have decided this buy in a small quantity and also apply the same concept to selling as well. I never sell or buy all at once instead of for smaller quantities.