I would recommend hiring a guide, get 6 or 8 together and the cost is not too bad. They know the way down to avoid falling into a crevice. The only intimidating part when you exit the second needle at the top and need to descend on steps cut in the snow down a knife-edge snow ridge carrying your skis (it has a rope railing). Sometimes the guides will rope you together for this, sometimes not. It is 10,000 foot vertical drop on the left, only about 1,000 foot on the right. Of course, it really is not a vertical drop, because I saw some hotshots click into their bindings and head straight down the left side chutes.
Anyway, after a 200 foot descent on the steps, you get to flat spot where you click into your skis and head down following the guide. It is really quite easy thereafter with just one steepish part. The guide will instruct you before hand, under no circumstances should you ski past him (or her). "I stop, you stop above. No ski by me!" That is because when he stops, he has come to a crevice and is scouting the best route around. I got close to one and it is scary.
By all means, ask him to stop for lunch at the refuge on the side of the glacier. All supplies (and staff) are helicoptered in. And if he asks "Do guides have to pay for their own lunch?" Tell him you're buying.
Hopefully you can ski all the way to Chamonix down a switchback catwalk which can get very icy. Otherwise, you will have to climb a staircase, equivalent to an 8 story building to the cog railway station and buy a ticket to ride down.