Max out any tax sheltered accounts (401k, 529's if you have kids) first. As for investment choices, low fee index funds (Vanguard is great). You can make your own allocation but generally if you're young it's recommended to have 90% stocks / 10 % bonds. Can be divided in different funds. I personally have about 30% in Total International Stock Index, 30% SAP500, 10% Emerging Markets, 10% REIT's, 10% Total Bond Fund, 10% small cap index fund. Rebalance every 6 months
(spreadsheet to help) and otherwise DON'T TOUCH it. If all of this is quite foreign to you and you're not interested in the nitty gritty, can also invest in Target Date Fund for your age and get similar results with basically no work whatsoever. Most importantly...DON't TOUCH IT. You can't time the market no matter what anyone on here or in real life will tell you. Invest over time and stay the course.