You will never win the lottery, so you don't really need to read this interview with Jason Kurland, a self-described "go-to" attorney for lottery winners. It's still interesting, though.
From Vice:
OK, so what's the first thing you should do if you have a winning lottery ticket?
First thing, you want to sign the back of it, because [a winning ticket] is what's called a bearer instrument—technically whoever hands it in is declared the winner. If you sign the back of it, you secure that it is yours. And I tell the big jackpot winners to sign the back, but to leave some room above it, because if we decide to claim it in a trust fund or an LLC or any other kind of entity, you will be able to write the name of that entity above it, and then sign as a trustee or something like that. So sign the back, make a copy of it, and preferably put it in a safety deposit box, or hide it somewhere in your house.
Then what you want to do is start hiring your professionals. You want to call a lawyer for sure—I am talking about if you win $1 million or more, you should do this stuff. Call an attorney, a financial planner, an accountant––that's the team you're gonna need. Obviously the bigger the jackpot, the more necessary it is to get a team like that. Get your team in place, keep quiet, and don't tell anybody. You can tell your immediate family, but as soon as word gets out your life is gonna change, and you don't want your life to change unless you're ready for the change. That time between knowing you won and claiming to the whole world you won is like your last chance of keeping your old life the way it was.
Then figure out how you want to do with the money, because everybody's first instinct is never what they actually want to do when they think about it. So you need that time to figure out what you want to do. Then at least nobody is banging on your door asking for handouts.
