Basically to gain in sexual experience I'd like to have something between a girlfriend and one-night stands, like FWBs/"plates" or in other words having 2+ girls to frequently have sex with but without commitment.

However, how do you make sure the relationship evolves and stays into FWB and NOT something committal and exclusive like a serious relationship? And which signs tell you that you are in the FWB path and not the serious relationship path?