Every trader, no matter how skilled, has losing trades. Stop losses help you manage are a great tool to help you manage your risk and keep your losses small when a trade does not go your way.
Always have a set stop loss or some kind of set exit condition (if you are using an automated trading solution) to help you control how much money you lose in a bad trade. This will allow you to keep your capital and continue trading in the long term.
Avoid setting stop losses randomly.
If you are setting a fixed stop loss, place them behind one or more areas of probable support/resistance. If the market you are trading is more volatile, you may place your stop losses a little further away to compensate for that volatility.
BirbicatorPRO provides several different visual indicators such as price bands, fractal pivots, and auto price levels that can be used to quickly find great places to set your stop losses.
After you find your stop loss, make sure to adjust your position size using the principles described in the Risk Management section to help keep your losses minimal.