Forex trading psychology is a big thing. Often, it is the psychology, and not a lack of academic knowledge or skill in application, that is considered to be the primary originator of trading mistakes. Mistakes are constantly repeated by financial traders of various national, cultural, and social backgrounds, which suggests that it is the common traits shared among us as humans that lie in the base of those mistakes.
Loss aversion bias derives from the prospect theory. Humans have a funny way of evaluating their gains and losses, along with comparing their perceived meanings against each other. For example, when considering our options before making a choice, we are more willing to give preference to a lower possible loss over a higher possible reward. Fear is a much more powerful motivator than greed. In practice, a trader with a loss bias is more akin to cutting profits when they are still low, while allowing bigger drawdowns.
The 2nd method is by performing a carry trade, where you can profit by buying a currency with a higher interest rate, and selling a currency with a lower interest rate. An example of this would be the USD/CHF (Swiss franc). If you buy USD/CHF, you are buying the USD, and their interest rates are higher than Swiss interest rates, so if you hold the position overnight, every day you hold the trade you will make money, and the money will be deposited in your brokerage account.