Get ready for the fact that it is extremely difficult to conduct a multiple relationship and sooner or later they lead to collapse.
You can not only lose one of the partners, but two at once. But if you decide to take such a step and do not build anything serious, then develop memory first.
You need to remember what you are talking to each of your girlfriends and remember all your excuses about where you slept last night.
Avoid places where you could potentially cross with one of your girls while you are on a date with another.
On the Internet, everything is much simpler, just do not forget what you write about.