I would suggest keeping a proportion of your portfolio in 'old money' on exchanges which provide direct access to buying the main tokens. E.g. Bitstamp, Kraken, Gdax, bitfinex, or others. Then, you are ready to buy immediately when the opportunity (crash) occurs! Ideally, sell just before the crash too;)
RE: Crypto for the Average: How to handle Crypto Market sell-offs like today (6/26/17)