just make sure you are prepared for it to all fall apart, im not saying it will, but if it does and you're not prepared then it could mess you up...(this kinda happened to me quite recently, dunno if uve read my thread...)
does she want the break more than you? if so then maybe its best to end it now, in that case she probably doesnt want to be with you as much as you do, and just cant face telling you straight out or something. Either that or she wants to date other guys to see what its like + then she'll come back to you, do you want her back like that?
if its a mutual thing, and you are both in the same place, both wanna see other people and stuff then theres not really any harm in it, but then if u wanna do that why is it a break and not just splitting up?
to be honest, i dont think after a break a relationship can get better, its usually because there are some kind of problems which wont go away, or simply that one of you doesnt want the relationship enough.
as for rules, thats for you two to decide! i would try and have a proper talk to her, not any of this break ****, ask her y she wants a break, y do u want a break if u do? and try and sort the relationship out by talking, a break is something that people sometimes feel they have to do, but i dont think it actually ever helps things, u need to talk...
hope this is useful advice