Before you risk your cash - put yourself through some practice drills first

There is nothing to keep you from investing in mutual funds and buying your own stocks as well. 

Much of the advice here is useful:

• the advantages of starting early,
• of having a plan,
• of sticking to the plan, and,
• of not worrying about crashes and corrections.

How do I figure out which stocks to pick or which fund to invest? Where do I get the money to buy them?

Since it's dangerous to put money into stocks before you figure out how to pick them, you should put yourself through some practice drills before your risk your cash. 

You'd be surprised how many people lose money by investing in stocks before they know the first thing about them!  It happens all the time. 

A person goes through life with no experience in investing, then suddenly receives a lump-sum retirement benefit and throws it all into the stock market, blind, when he or she can't tell a dividend from a divot.  There ought to be some formal training for this, the way they have drivers' ed in school.  We don't put people on the hghway without giving them a few lessons in the parkng lot and teaching them the rules of  the road.

If nobody else is going to train you, at least you can put yourself through training, trying out various strategies on paper, to begin to get a feel for the way different kinds of stock behave. 

Again, a young person has an advantage. 

• You have the luxury of experimenting with imaginary investments, at least for a while, because you have many decades ahead of you. 
• By the time you have the money to invest, you'.ll be fully prepared to do it for real.

Comment: 
The safest and best way for young investors is to have a mentor with a proven track record.