I wouldn't call myself a fiscally responsible person, but I chat about finances a lot with folks and the best advice I've heard in general is if you've got extra money and you're looking to "invest" it for your future, the first thing you should be doing is setting up and contributing to an IRA. Set yourself up a Roth IRA and contribute your max ($6k/year usually). Good thing to do is set that IRA up with an index fund with a target year of when you plan to retire (2045, 2055, 2065, etc). Index funds are a relatively safe place to earn money for retirement, but it's also good to diversify and put those funds into different things.
I know a lot of folks who work in places that don't have pensions or 401(k) plans or the like, and I try to tell them you should be trying to put some money into an IRA because social security only covers at best 40% of life expenses after you retire, you need something else or you're gonna be working when you're 80. And even if you've got a 401(k) or a pension, it might not be enough, so consider other options as well. Plus the more things you've got earning you money, the earlier you can retire. And if you do work somewhere with a 401(k) don't sleep on that, especially if your company does matching, if they do matching take full advantage of that minimally... most folks suggestions are contribute 15% of your income. If your company only matches 5%, minimally put in 5%. Since your company only matches up to that amount, anything over that amount is entirely you, so you could do 5% through your 401k on an index fund and then set up a separate IRA and contribute whenever you've got extra money.
Another thing is the differences between traditional IRAs and Roth IRAs. Roth IRAs are paid after taxes, so when you take it out down the line you aren't taxed when taking the money out. Traditional IRAs you don't pay taxes on the contributions, but you pay the taxes when you take it out. A lot of folks look at that and just blanket state that do Roth IRA because taxes will only go up, but something to consider is that if you are making so much money that you move into a higher tax bracket, you're taxed higher, but if you contribute to a traditional IRA it can lower you back down to a lower tax bracket saving you money when it comes to doing your income taxes.
Someone feel free to correct me if I'm wrong on any of this.