Here is an article talks about how to choose an online stock broker.

Introduction

Choosing an online stock broker can be difficult and overwhelming at times. People new to stock trading and investing have many choices and options to consider. Finding the right online broker to meet your needs or requirements can be very rewarding and beneficial, for your portfolio and your peace of mind.

Here are some basic things you will need to consider when you look at difference online brokers. If you are not sure what these options and features are, you can speak to a representative of an online broker firm, or you can leave a comment and we’ll do our best to answer your questions.

Commissions

All brokers charge commissions fees. Commissions fees are the cost to buy and sell stocks. You are charged a commission fee twice: once when you buy a stock, and again when you sell that stock.

I believe all brokers charge higher commissions when you phone in orders and speak to a human being. Keep this in mind as these commissions are for orders placed online only.

• Scottrade: $7 per trade
• TD Ameritrade: $9.99 per trade
• Interactive Brokers: varies, minimum $2
• E*Trade: $19.99 per trade

Minimum Initial Deposit

The minimum initial deposit for online stock brokers ranges from $500 to over $10,000. For those with less initial trading capital, lower minimum deposits are generally the deciding factor.

If your account balance is less than this minimum, your broker may charge you a fee every month or every quarter. These fees usuall range between $10 to $20 per month or per quarter, but can be higher. Read the fine print if you plan on depositing the absolute minimum capital in to your account.

• Scottrade: $500 minimum deposit
• TD Ameritrade: $2000 minimum deposit
• Interactive Brokers: $2000 minimum deposit
• E*Trade: $1000 minimum deposit

Features

All online brokers have a set of features and tools included with your online trading account. The default set of tools include streaming charts and streaming data, which is usually in the form of an application called a streamer. Your streamer allows you to see the latest real time prices of stocks in your watch list or portfolio. Some streamers simplify the process to buy and sell stocks so you will not have to load up a separate web page to place your orders.

Most brokers also have additional features which are not included in the basic trading account. These additional features have additional costs. Level 2 data and real time streaming news generally fall in to this category and have additional monthly fees.

Popular features offered by online brokers include:

• Streaming Charts
• Streaming Data
• Analysis Tools
• Streaming Real Time News (may cost additional fee)
• Level 2 Data (may cost additional fee)

Local Offices

Some online brokers have local branch offices some U.S. cities. Some traders and investors may want to sit down and talk to their local broker representatives. In this case, choosing an online broker with a branch office close to your home may be the deciding factor for you.

Scottrade has very many branch offices all across the US. TD Ameritrade also has branch offices in some cities and the number appears to be growing. I do not believe E*Trade has any branch offices.

My broker, TD Ameritrade, has an office in my city, but I have never visited them. A local branch office was not a deciding factor in my choice of an online broker.

Popular Online Stock Brokers

Here are the most popular and respected online stock brokers. This list may be incomplete or your favorite broker may not be included. These are the brokers I am either personally familiar with or have heard good things about from my trading and investing friends.

• TD Ameritrade - my online stock broker
• Scottrade - my old online broker
• E*Trade
• Interactive Brokers

Something to add to the above article: 

commission fees and minimum capital requirement may not be representing the current situation.  plz check online to see the latest information.