I think I've put this up before, but it could probably use another airing.
http://www.virginialegaldefense.com/tempname/LetterToCops.pdf He counsels very strongly that you should be prepared both emotionally andf financially to be locked up for up to 96 hours if you go that route. He does not suggest that will normally be the case. but that it may be and you need to accept that as opposed to waiving your rights shortly after the door bangs shut behind you in the hopes you will be let out after you have changed your mind and spilled your guts. He also counsels setting up a phone tree of sorts so that the first person you leave a voice mail message with (possibly your one and only free phone call) will start getting folks together to donate bail money and to start folks calling him to remind him you are in the pokey.
He says that if you cannot afford to be locked up for a few days then consider just how much you can say and then stop talking that will convince the cops to let you go. And to call him ASAP anyway.
He and I disagree on whether making statements such as identifying the person(s) you allege are the assailants, wher evidence that is not in plain sight may be found (unser which bush or in what garbage can), and who you believe were witnesses are covered in the "Shut your mouth" instruction. He says "say nothing" means just that; I suggest that some information given at the scene can actually be helpful to you as well as the cops.
All of the above, of course, is worth exactly what you paid to read it.
stay safe.