As we have spoken earlier, a higher time frame should be used as guide.
It is however very important to decide and fix the time frame which a trader would be using on his charts for trading purposes.
For example if one is using 15 minute charts for trading, then hourly charts or 30 minute charts can be used as trend guides.
BUT.....the trading entry and exit rules as well as stop loss rules should completely stay within the 15 minute frame. Once entry made, stop loss and profit targets should not be modified by reverting back to 30 minute or hourly time frames.
IT IS VERY IMPORTANT NOT TO FIDDLE WITH THE TIME FRAME ONCE DECIDED UPON. THIS IS AN IMPORTANT FACTOR IN THE SCHEME OF DISCIPLINE.