You just won $540M -- now what?

This post comes from Jonathan Gill of MSN Money.

Somewhere out there, one of you just might get lucky on Friday night. Really lucky, by winning the $540 million Mega Millions lottery. Never mind the odds (1 in 176 million) or that you stand a better chance of getting killed by a meteorite (1 in 700,000) or struck by lightning (1 in 280,000).

Though your chance of winning is nearly zilch, it is possible, and someone will eventually win. So, if it turns out to be you, congratulations. But what do you do next?

How much is that? First of all, let's take a look at the numbers. Say, instead of an annual payment of about $20 million over 26 years, you take the lump-sum payment of $389.8 million. But you have to pay taxes on that. Take-home pay will be something like 70%, depending on where you live, so let's say $273 million.

If you invest that conservatively (dividend stocks, etc.), you're still making $10.92 million every year. That's nearly $1 million every month or $100,000 every three days. That's without spending a penny of the initial jackpot. (Post continues below.)

Protect yourself. Hire an experienced wealth manager. Not your neighbor. Not your relative. Not the treasurer of your PTA, even if he does claim to know something about "investing."

"Oklahoma City attorney Richard Craig, whose firm has represented a handful of lottery winners, says it's essential to assemble a team of financial managers, tax experts, accountants and bankers," The Associated Press says.

Also:

• Consider setting up a trust.
• Consider setting up trusts for your kids.
• For more ideas, read Liz Weston's "You won the lottery! Now what?"

Give generously, but don't be stupid. People will line up at your door to ask for money. Your mailbox will fill with sad stories and investment "opportunities." Your friends and family members will feel entitled to some of your wealth. Don't let them control you.

Give to legitimate charities you have thoroughly vetted and that reflect your values, but beware of charities that come looking for you.

Set up a giving budget. Remember that $1 million a month of interest income? You have cash to spare.

You still need an occupation. Your first reaction will be to quit your job. Not so fast. Think about how you're going to spend your time. Vacations are fun for a week or two. But after a while, they get pretty boring. We all still need a purpose, a way to contribute to feel good about ourselves.

• Smart Spending on the go: Get our app for Android or iPhone

What will you spend your time doing? What's your dream job? Volunteering? Teaching kids? Building homes for Habitat for Humanity? Get out there and make yourself useful.

You still need to raise your kids. The die is already cast for you. But how are you going to raise your kids to be good people? Giving adults piles of money is risky enough -- plenty of lottery winners have lost it all -- but you still have your kids to raise. Don't ruin their lives. They still need to be productive members of society in the future, and you're still responsible for seeing that they get there.

Avoid excess. It's OK to buy a nice house. Don't buy five houses. Or an island. Or a town.

Lease your cars rather than buy them. You'll probably want to change them frequently, and you can afford to. You're a perfect candidate for leasing.

You can rent vacation homes, yachts and airplanes. That's a lot less hassle than owning expensive, high-maintenance things that get only occasional use.

Don't be tacky. Money doesn't necessarily buy you class. Spend to fit your surroundings.

If you live in the country, you'll look silly driving through town in a Lamborghini. Or a Bentley. Exotic sports cars break down and get easily stuck in the mud. Don't be that guy. Rather, spring for a loaded Ford F150.

You don't need a football stadium in your backyard. Instead, build a nice one for your local school if you like. That would be a lot more fun anyway.

You really don't need 50 D&G purses, or 100 pairs of Prada shoes.

Really resist the urge to get plastic surgery. You're not going to look like Brooklyn Decker or Daniel Craig, no matter how much you spend.

Karen Datko contributed to this post.

More on MSN Money:

• Advice for Mega Millions office pools
• Why are rich people such jerks
• 8 things rich people buy that look dumb
• How the rich pay no taxes
• Rich, famous . . . and in foreclosure
• Calculator:How much house can you afford?