There are a lot of variables here. And room for adjustment based upon those variables.
At 8 years old (3rd grade, right?), she should be able to put her clean clothes away, either in drawers or on hangers, and to know which is most appropriate for whatever article of clothing it is. She should be able to put her dirty clothes in a hamper and empty the hamper (weekly? or however often it is full) in the laundry room. She should be able to put her books on a shelf. She should be able to put her shoes in the closet, or line them up at the foot of the bed, or whatever you deem "adequate". She should be able to put the "clutter" in a drawer, or a bin, and put the "games" in their boxes and the "toys" (legos, barbies, lincoln logs, whatever) in their storage bin/container. She should be able to pick up misc electronics items and put them where they go (in a bin, in it's case, on the shelf, whatever).
Now, the problem can be that there is just plain TOO MUCH STUFF. When it gets to that point, then she has no idea what to do or how to start. So yes, you need to help her get going by laying out an order and helping her get things sorted out to a manageable level. Once it is all finally cleaned/organized/eliminated (some things just have to GO), then she ought to be able to keep it in relatively picked up/put away condition on a regular basis. Allowing that, probably every few weeks, you're going to need to pop in there for an hour and help her re-sort and re-get it into tip top shape. Eventually it will get easier for her. But in the beginning it can just be overwhelming.
My son, after YEARS of fighting over this problem of his room, finally, FINALLY (at almost 13 years old!) realized that he was just holding onto too much STUFF. I have always had a battle removing any old toys or even literal garbage (the packaging from toys that have pictures or instructions on them type stuff) from his room. But I kept on going through it a few times a year. I'd go in and clean it all out and put away, and organize anew. It would sometimes take ME 2 full days! He just had too much stuff with little parts/pieces. It all had containers for it... but things always got mixed up. And having all those containers made it an overwhelming task to clean it up.
NOW, he is starting to do it on his own. He cleans one AREA of his room at a time. Today the desk. Tomorrow the computer station. The next day the closet. Next day the dresser/bookshelf (ipod dock, CDs, stereo, watch, school papers, etc). But HE is doing it.
Some kids are more easily overwhelmed than others...so just stick with it and guide her.
I truly believe that one of the reasons it is such a common issue today (and WASN'T when we were kids) is the sheer volume of STUFF that kids have today. I mean--we didn't get a kids meal toy EVER. And "goody bags" from birthday parties? Unheard of. Teachers giving out toys at school parties or for prizes for doing well on standardized tests??? Didn't happen. And our grandparents NEVER spoiled us with junk like today's generation does. I couldn't tell you one thing my grandparents bought me. They didn't have $ for wasting on plastic junk.
Teaching her to throw out, donate or otherwise get rid of things she REALLY doesn't know what to do with is hard, but it is a wonderful skill that a lot of ADULTS are sorely lacking.
Hang in there.