maybe with hold half for a price increase, i think the end of the year will reach $400 and I will sell it, quite profitable
That is good option, always trade with small quantities what you have then you can get over all better prices when you sell or buy at different levels.
Yes. Buying with all our money at one price is not at all recommended. You must wait for price up or down always, if price go down you can buy again which means you are getting a better average price. This is a general thumb rule of trading. So, it applies to bitcoin trading also.