Maybe you will be able to figure out how to sell BTC in order to accumulate more BTC, yet it seems to me that in your earliest years of BTC accumulation you should not even try selling BTC to try to accumulate more, and you should merely be using various kinds of buy strategies including DCA, buying on dips and lump sum buying. The more BTC you accumulate the more options that you have, and the more BTC you accumulate, you can attempt to assess the status of your own BTC holdings (including how much they are in profits - presuming that they are in profits) and also how much they are worth compared to other kinds of investments (which also may well including your various currency/cash holdings) that you have.
Yes ! One shouldn't sell BTC to buy more BTC, fine it might seem like a strategy but not a good one because we are dealing with future event and you might end up losing out of your BTC which is opposite of what you are expecting .
However, there are good strategies out there and it has been listed by JayJuanGee and what fits the analogy of accumulating more btc without selling most is buying the dips as you don't have worry about the sell limit , you should just keep on buying the sell.
Thus, trying DCA gives room to no worries either the market is experiencing a dip or not, just keep on buying the fixed amount and you will start seeing some nice average results of your buying.