MetaTrader Australia

The current price shown on an MT4 chart is the bid price. When looking at a price bar or candle, you must add the spread to the high bid price to know what the high ask price would have been, or add the spread to the low bid price to know what the low ask [...]

You receive the “Trade context is busy” message when you try to process two or more orders at the same time. If you have placed a trade and do not wait until it processes completely and then try to place the same trade or a different trade, the commands go into a loop and you [...]

Templates can also be created for charts opened from the Strategy Tester and for charts opened independently.
To create a default template for charts opened from the Strategy Tester, you will need to save a template as “tester.tpl”.

For offline charts, the default template must be “offline.tpl”.

If the “offline.tpl” template is not found when an offline chart [...]

Use F12 to move through a chart bar by bar.
This function can be very useful when you develop and test your own trading strategies. Simply open a chart at the very beginning of the history (press Home) and move through it bar by bar.
Shift+F12 will move through the chart backwards.

Source: http://articles.mql4.com/189

By using Chart Templates the chart background, bars colors, indicators and objects can be saved and used on other charts.
To do this, setup any chart as you wish: set colors, superpose objects, attach indicators, etc. Then select the “Charts -> Template -> Save Template…” menu and save the obtained template as default.tpl

When placing orders from charts there is no need to remember which type of pending orders to use.

To place a pending order via a chart just right click with mouse on the desired point in the chart where you would like to place the order and select the “Trading” command in the menu. You will [...]

If you have several trading accounts, you are able to create a special profile for each account.
When you switch between accounts, the profiles will be opened automatically.
To create a profile, you must save it under the name which is exactly the same as the account number.

Source: http://articles.mql4.com/189

If you accidentally close a chart it can be reopened with all its settings using “File -> Open Deleted”.

Source: http://articles.mql4.com/189

To back test an expert advisor (EA) follow the steps below.

Open the Strategy Tester window by pressing Ctrl+R
Select the expert advisor you wish to back test
Select the symbol you wish to back test
Select a testing model (every tick model recommended)
Set a testing period
Press Start

To modify a working order or create a new Stop Loss and/or Take Profit order, double-click on one of these fields in the order line.

When the order window appears, enter the necessary values.

Source: http://articles.mql4.com/189