What do I buy or sell while trading the VIX?
If you have to ask that question, you probably shouldn’t be trading it.
Unlike stocks/ETFs/options, the VIX has no real underlying assets. If you buy/sell call/put options, when those options “expire”, the VIX settles in “cash”. So if your option expires “in the money”, the cash value is added to your account.
I have traded VIX options a few times, but don’t really like it because the premiums aren’t close to what I look for. Hope that helps.