In addition to the above advice on pre tax and post tax accounts:
Before you invest, consider building a bank or money market savings account to include 6-12 months living expenses to cover any would be financial emergency.
Afterwards, you should also consider a risk tolerance test to determine your best mix of investments to include stocks, bonds. commodities, real estate , cash, ect. . You may be able to take this test through a local financial professional or from the larger mutual fund companies such as Fidelity or Vanguard. These investments may be available to you in a retirement account such as a 401(k) or and IRA depending on the choices available to you.
