The quickest way? Stock market.
The safest way? Anything but stock market. But seriously, it's government bonds (unless you live in Greece or Spain

)
If you throw in 10k to one and never touch it by the time you retire it should be worth around a million.
Assuming you're going to retire in 40 years, that's 12,2% APR. Somehow I doubt it's possible in term deposits

But yes, the sooner you start investing the better. Every year makes a huge difference when you're thinking long-term.
I said it works for young people, not me.

It's pretty simple I forget the name of the accounts but it's a CD or something your money gets locked in for a set period and periodically the interest rate will go up until it gets to around 15% or so I forget the specifics but it adds up after 40 or 50 years.
This sounds like progressive deposit, but I don't think any bank offers such long-term CDs. The longest are usually several years with the possibility of renewing.
Anyway, they're not as profitable as they sound. The interest rate starts out low and grows every month, but it obviously takes time until you reach the highest numbers. So a 12% deposit will average out to ~6,5% effective APR. It's still better than regular deposits though (if you manage to find one with a decent interest rate, that is).
You should think about investment funds (preferably balanced or growth-income - or whatever it's called in English). Diversification reduces risk and if you're lucky, they can be fairly profitable. There's also so many types of them that you can always find something interesting. Disadvantage - commissions.
It's a good way to learn how investments work before you dive into the big world of stock market
