When you ready to start investment, you need to make decision on what type(s) of investment you want to do.
There are the following choices: stocks and options, bonds, mutual funds, gold, precious metal, or other commodities.
After you made the above decision, you might need to choose one or more investment brokerage companies.
There are several types of investment institutions:
(1) Discount brokerage companies: they usually charge lower fees and commissions.
In USA, E*Trade, Scottrade, and Ameritrade are the leading discount online brokerage companies.
(2) Full-service brokerage companies: they usually offer investment research and/or advise services.
(3) Mutual fund companies: e.g. Vanguard or Fidelity, they provide mutual funds trading.