1. Max out 401k and take advantage of employer matching. 2. Max out Roth IRA. 3. Invest in low cost index funds/ETFs.
Good overview: https://www.pbs.org/newshour/show/all-the-financial-advice-y...
Bogleheads Wiki is the definitive resource, Start from the Getting Started page: https://www.bogleheads.org/wiki/Getting_started
Once you grasp the essentials, you can deep dive further with the recommended reading list: https://www.bogleheads.org/wiki/Books:_recommendations_and_r...
If your employer offers a 401k with a match, you should do it.
To invest outside of an employer fund, you can open an account with any number of firms, but many folks like Vanguard: they have low fees and aren’t trying to up sell you.
There’s a vibrant community at bogleheads.org (their wiki is probably more useful, e.g., the three-fund portfolio). I think there’s a subreddit at r/personalfinance or something that’s reasonable as well.
As others are saying: use simple index funds, maybe even start with just a target date fund if you aren’t comfortable building your own portfolio.
401k is pretax. Usually you can change settings whenever you like though it usually takes a pay cycle or two to take affect. Pay yourself first (invest/save automatically) and budget with the rest. If you have goals like buying a house don’t forget to save for those separately so you don’t have to dip into retirement funds early and get hit with fees and extra taxes.
I think this video[0] fits nicely to your situation. JL Collins lays out how to invest for your retirement using index funds, explained in simple and commonsensical terms.
You've said nothing about goals. I'd say start there and work your way down.
I’m going to suggest wsb. Start with a small amount and try to have fun. Add more as you gain confidence and determine your risk tolerance.
Research target mutual funds. They're all many people in your situation need.
/r/bogelheads
It's very hard to beat index funds, few funds beat them year after year. So, call a mutual fund company(vanguard is very good) and tell them that you want to invest in index funds. They will guide you on what to do.
Add funds on a regular basis until you need it. It will grow. Keep in mind that the returns will be a wavy ride but ultimately it will be positive.
We are starting to hear criticisms on index funds but we have yet to find a better long term way to grow wealth for the individual investor. Specially for people that don't want to make finance there life's work.