Mind you the time to have done this is before the decline not in the middle of it.
That said, what follows applies to stocks as well as cryptocoins.
1 Use a balanced portfolio. Now I would use 3 different cryptos plus some fiat currency, but you can use more.
2 By balance you could keep an equal amount (as measured by their fiat valuation) of each crypto. Now, it doesnt have to be equal. You could use a ratio if you think one crypto is a better chance. Another reason to change the ratio is if you expect a decline and wanted more in your fiat account.
3 once your cryptos are balanced the way you want them, watch for one to get $500 (as an example since my fiat is USD) over or under the other coins. When this happens, sell a little of the coin thats up and buy the same value of the one thats down. This is how you balance and you might notice you're selling high to buy something low.
Here some links to other articles that could help you.
https://steemit.com/investing/@toadslinger/improving-investment-profits
https://steemit.com/investing/@toadslinger/improving-investment-profits-pt-2-of-7
https://steemit.com/investing/@toadslinger/improving-investment-profit-pt-3-of-7
https://steemit.com/investing/@toadslinger/improving-investment-profits-pt-4-of-7
https://steemit.com/investing/@toadslinger/improving-investment-profits-pt-5-of-7
https://steemit.com/investing/@toadslinger/improving-investment-profits-pt-6-of-7
https://steemit.com/investing/@toadslinger/improving-investment-profits-pt-7-of-7
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