DO NOT sell (especally if its ADA or ETH...those two are going to places you can't imagine, just have to have patience). Once you sell you will have to pay capital gains taxes. In fact I would even suggest you stake your ADA if you have a lot. You can stake ETH as well but you will not be able to trade ETH once its staked until 2.0 launches so be careful.

Another loophole to keep in mind is wash sale rules DO NOT apply to crypto. If you're at a big loss, just sell and buy back immediately. You will be able to deduct that loss. You can't do that with stocks.