While friends with benefits is a common relationship type, it's not one that is without its challenges. In order to have a successful FWB relationship, both parties must be on the same page in terms of their expectations and desires.
There must be a clear understanding that this is a purely physical relationship and that emotions will not get involved. If there are feelings of attachment or love developing, it's important to address them head-on to avoid any hurt feelings down the road.
Both partners must also be honest about their other sexual encounters. Jealousy can quickly ruin an FWB arrangement, so it's important to be open and honest about any other hookups.
Overall, as long as both parties are on the same page, an FWB relationship can work out just fine. There may be some bumps along the way but as long as communication is key, everything should work out swimmingly in the end.