well its your choice , you can reinvest in your services to get more profit, you can go for mining, you can buy some altcoins or evn you can go for gambling on your own risk and you can have fun, buy some things you really like or keep in your wallet for the increment of the price:)
Yeah, I think the best way to approach this problem is to simply hold your bitcoin until a week before the halving and sell it. And then when the price crashes, invest all your fiat again.
Trading bitcoins can be extremely profitable.
I don't think there will be a crash per se, but alot of instability after the halving, as the market tries to settle. I'm prepared to do a little buying and selling myself. I'm expecting jumps up to +- every day!