On popular minecraft rp servers there is an action /me (Type your action).
This was also added into skype :p.

A thing about rp, is you need to be descriptive and fast.
Eg
I walked to the boy. (Wrong).

I pick up my pace a little, while walking on the cold damp ground, towards the lonely looking boy.(Correct!).

Out of both of these, you can easily get a better idea of the situation by the second one.

Another thing in rp you cant do is Meta Gaming. Dont go up to someone and kill them with a "Knife to the stomach". Its better to say " Sprinted past the boy, attempting to slash as their side".

Lastly, if your roleplaying as characters for eg Kaneki and Ayato (Before they met), you cant use the info you have in your head, in rp. For eg "I walk up to Ayato and say Hi".
You cant do this, because you know the character, but you have to establish the info in rp, for YOUR CHARACTER doesnt know this info.
"Walks up to the irritated blue haired guy, greating him, asking his name." (Correct).

HOPE THIS HELPED.