RPB isn't that different from a forum RP thread, except that it's more...how to say, intimate?

Allow me to explain. In an RP, you collaborate with others to advance the story, by composing the action taken by your character and how he executes the action. The more elaborate and vivid the composition is, the more enjoyable it is to read. Each piece of the story becomes a jigsaw puzzle that blends into a whole story, as chapters of a book.

But I assume you know that. It's just for the purpose of placing a brief description to which to refer in case of comparison. Of course, one part of the RP that the RPB lacks is the presence, at times, of a moderating participant, which holds the reigns of the storyline, which determines what can be allowed, and what can be disallowed.

In an RPB, similar rules apply, but with certain differences. When I speak of "intimate", it's because only two people participate, and the entire flow of the small battle flows from the combination of both minds. One may define the boundaries of the story, but at the end, both people have the potential to alter the story as they see fit. The actions are purely the definition of a combat action, which may include, and are not limited to: flashbacks, lapses of thought, speech, and the movement in itself. Each action constitutes a turn, in which the action is responded as it deems fit. You can either take the hit, block/parry/evade or otherwise null the effect of the attack, apply a move to reduce its effects, or even a limited alteration of the move (this one can border on god-modding, and it should be agreed on both parts). The true degree of intimacy is on the discussion of the move. For example, say that I deal an attack with, say, a fireball: a very typical spell. Normally, you either take the blast, or block the fireball with either a physical or magical barrier. Yet, to really add the depth of knowledge and control, you decide that's better if the fireball explodes, yet the pressure wave and the flames swirl around you, as part of an effect of a protective ward placed upon you beforehand, or even as a reflexive action. You may think that such a move is possible (in the realm of one's mind, anything is possible), but the other person may not agree to such. Yet, if you discuss beforehand the effect of your ward, and that you may exert a bit of personal power to alter the effects of a move slightly, and the other person agrees, then the action becomes more fluid: both people agree to allow the move to be altered, and by no means it should be considered god-modding. Only the abuse of said privilege can turn into god-modding, or in the case where the person is simply undefeatable. One simple premise must be always followed: in the realm of RPB, no matter how cool your character is, he's always vulnerable to something. One of the infinite possibilities of moves of your character should be able to at least dent the defenses, and shake the confidence, of the opponent. If the person is truly undefeatable by some specific circumstance, then the battle becomes un-fun, an undesirable end.

One of the things that often works is that the RPBers often communicate via PM, or by instant-messaging programs, to gain feedback on the moves that will be executed, and how the other reacts to it. Communication is essential (one of the things that apparently seems to be a flaw of mine). Writing technique is also key: each person has its own writing style, which can cause conflict upon the other. In essence, the victor of an RPB often has the superior, or the edge, in the writing style. The way one describes the action, and how it affects the opponent and the background, eventually becomes the judgement by which a winner is declared.

And getting into the mood is essential: write while listening to music, think of ways to solve a particular problem every moment you can, and also think that the more glory you hog, the less entertaining the battle is. The battle should be a swing, a dance of actions, in which the other person can be granted a chance to shine, or else, the battle is abandoned, and the victory is sour.

That's mostly it. I think I get here, and I get inspired in writing one-hour long posts just for the heck of it. I tend to exaggerate the length of my posts with flair and long words.

As per Jaffar, well, the degree to which the skills should remain locked or not should be settled upon the discussion. I agree that, to reach the proper potential, your character should be free to undertake its own actions. Thus, it should be capable of executing all of its actions, and perhaps even add a few more. In the RP, since it should give the impression that they were beginning their journey, they had to begin at a lower level. Not in this case, where they should be facing at an equal degree of power, perhaps with a slight handicap if so desired and agreed. I'll explain more via PM, to determine if the idea running up my mind sounds right to you.