You can't be sure. Nevertheless, each TF has its own, so decide how you are going to trade, then zoom out on that TF until you have a few weeks, or more on the chart, decide where the ranges are and draw the lines.
This is not mathematics. It is hit or miss, IMO, and the lines that you draw must be looked at as zones, not turning points in themselves.
look at the support and resistance levels for areas that have been tested multiple times, plot it and give yourself room for error to filter out spikes, etc.