Common fee types that lose you money
This fee traditionally will be a fixed number, it doesn't matter how much money you are transferring - the service fee stays the same. Keep in mind, this can across from providers.
Exchange Rate Markup
The service provider usually shows you an exchange rate, but this rate is not always the current market rate. This means that your recipient receives less, and the provider keeps the difference between the rate given & the actual market rate.
Additional fees can be tricky. Sometimes the recipient's bank will charge them for receiving money from another currency, in some cases this can be as much as the initial sending service fee. Always check the information about the recipient's bank too.