This is the question that I am always asked and it is an important question for the novice traders.
When you start learning and trading forex, you do not know on what time frame you should focus. That is why you try all time frames to see which one works better. You may think that smaller time frames are better, because they will have more trade setups and so more opportunities for making money. This can be true, but the problem with the smaller time frames is that they need you to sit at the computer and watch them for several hours per day and this is not easy.
Bigger time frames may have less trade setups but the good thing is that you can check them less frequently. For example when you work with the daily time frame, you can check the charts only once every day.
It is recommended that novice traders work with the bigger time frames like one hour and 4 hours. Small time frames like 5min are not suitable for novice traders at all. The reason is that controlling of the emotions is the most important problem that newbies have and when they work with the smaller times frames, they will have more emotions because they have to be fast. When you work with 5min chart, you have to decide much faster than 4hrs chart and it will be harder to control your emotions when you push yourself to decide faster.
If you are new to forex trading, you’d better to start with one hour or 4hrs chart. I do not say daily chart because it may look too slow to you. Smaller time frames like 15min and 5min can not be recommended at all. However, if you like to try the small time frames, you should do it with the strong and liquid currency pairs like EURUSD or GBPUSD, because you will have less number of false signals.
Also you should avoid trading on Sunday and Friday afternoon, because you will have a lot of false signals. The best time to trade using the smaller time frames is the London session which is the strongest and most liquid session in forex market. New York session is also good, but you will have more false signals in comparison to London session.
As you see there are a lot of things that you have to consider. Working with the wrong time frame at the beginning of your forex trading journey can cause you to get disappointed and give up. You need to analyze your trading style and find the problem. If the problems is related to time frames, you should switch to another time frame that is more suitable for you.