I'm a retoucher and will start also photography more professional. Here are a lot ofprofessional photographers and I'm not sure, what the big advantage and thedisadvantage to use a Nikon D800 by a beginner. I'm crazy to took fashion photosin a studio and also outdoor, but I don't have so much  experience with a flash.I need some advice, but independend of money. Please answer in Englisch, because I don'tspeak German well.

Hello Andrea.
The D800 is not a typical Beginner-Camera. It is a professionell Highend Camera, that requires some skills. Entrylevel-Cameras are generally more Beginner-friendly, since they offer special modes, that fit the needs of a Beginner. The D800 lacks such modes. They are available up to the D600/D610, all Cameras above (D800, D4, Df) can not be operated by a beginner out of the box.
Taking pictures is more a question of your skills, rather than your equipment. It's indeed the photographer who actually takes the picture.

Pleas note as well, that the lenses you'll need to match a D800 are much more expensive, than the camera itself.

But even if you have so much money on hand, you will not be able to take the pictures you want without consolidated knowledge.
Go for a D5200 (which offers everything a Beginner could wish), some decent glass and some accessory and train yourself in photography. Than come back in a few years and buy the successor of the D610, D800 or D4.
Cheers!

If you think you like the camera, just take it to start, But: take the bucks and join a technical workshop (guess Calumet offers it). Hiring a Pro for a day and receive practical informations would be necessary too. 
Ita a bit like start driving with a Porsche.

@KHM

you made my day guy....

"Than come back in a few years and buy the successor of the D610, D800 or D4."

independend of money...
...fashion photos in a studio and also outdoor

regarding color, sharpness, noise, graduation and resolution the D800 is pretty close to midformat cameras like hasselblad or phase one (I use hasselblads and nikons for many years now). though the D800 can not really compete to a real mid format cam, compered to the little money it is quite "close".

advantage of the D800 is the higher flexibility and it is much more handy (compared to mid format cams).

most of the pictures in my portfolio have been shot by D800 or hasselblad - I guess you can not tell a difference...

I tried the D4 several times but it did not satisfy me. I love those lightfeatures (when you use it in the dark everything is lit) and other nice "pro" things. but the results of the D4 did not convince me. I could not see a quality gain (compared to D800) and the resolution of the D4 is somehow outdated imo. so I stick with the D800 and D800E. I think the D4 is good for events and sports on high ISO. for press photography the resolution is quite good enough.

I do not think you need those beginner features like portrait automatic, landscape automatic or any other bullsh... this (imo) is useless and will not help anybody to get into photography. take the quick guide of the D800 and you will be able to make pictures right away with A, S or P mode. though in the long term it will be important to understand what these modes are good for (respectively what they are doing).

when you are looking for pro fashion shots don't forget to buy appropriate lenses. typical fashion lenses are high aperture lenses with a visible quality gain compared to consumer lenses. for fashion and people photography high aperture is a must (imo). nikons pro lenses are +1.500,- EUR each. I bought all the cheap shit before and other brands as well but after 20 or 30 lenses that I bought over years I am convinced that a good lense has to be 1000 or more. - which is quite cheap when you look at phase one or hasselblad lenses...

personally I see no disadvantage in buying a D800 if money is not an issue. a "beginner" camera will not help you to make better pictures I guess. the D800 works perfect in full auto mode. but in the end... a good camera is useless if you do not know how to get the best of it... so take your time :)

my suggestion for a fashion starter lens would be the nikon AF-S 24-70 2,8
it is very flexible in the studio and a fast lens with high aperture. my absolutely favourit fashion lens (and mostly used) is the nikon AF-S 85mm 1,4