These cutting suggestions work pretty good, however, your server may have his/her own way of doing things . . .

Two people are needed at each cake serving table; one person for cutting the cake and the other should be assisting with the plates, so that the person cutting does not have to handle the plates.  This second person also has the responsibility of replenishing plates, forks and napkins, removing the support plates, legs/dowels etc. from the cake and generally keeping the table tidy.
The first piece of cake is cut by the Bride and Groom wherever they find it easiest to stand to make the cut, and to be photogenic for the photographer. 

As they depart from the cake, the serving person should then put on latex gloves because this way, he can cut the cake with one hand and use the other to transfer the cake to the plate, held by the second person.  The gloved hands make the cutting and serving much faster, especially if you have a long line of people waiting for cake.

The top cake is removed (the second person may be needed to help remove the legs/dowels under the top tier).

Any flowers, hard sugar flowers and etc. on the next cakes down are then removed and sometimes placed at the base of the wedding cake.

The actual first servings of the cake come from the same tier that the bride and groom cut, and cutting as necessary to give you a straight clean line across the back of the cake (as seen in the diagram below).  

You start by cutting line 1, leaving about 2 inches intact on the right side of the cake (indicated by #5).
I hope this chart is of some help to you.  Sorry about the wiggly lines, drawing on a computer is kinda rough, lol.

The original cake cutting chart is from Earlene Moore of Texas, here is her link -- check it out:  l
Then, begin serving pieces from the edge, as show by #s 2, 3 and 4.  Now cut line #5. Cut the next line (#6), again leaving about 2 inches intact on the right side of the cake (incicated by line #13).CNow cut pieces 7, 8, 9, 10 and 11 then #12 as show in the to add text.
Wedding Cake Cutting Chart and Instruction Guide
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