I would say the process would be basically the same on any vector application you chose to use...
If you only want a silhouette then this will most likely be primarily a single object.
(i would assert)
But the steps necessary to produce a vector from a raster image would be different if you wished a colour graphic.

Assuming its a silhouette i would first manually create the outlines for all the "holes" (negative shapes) in the silhouette and then group these together when finished... then i would either cut these or copy them to a different layer for safe keeping whilst i did the main outline....
When the main outline was completed i would paste the holes on top and subtract them from the main outline shape.
Leaving you with your completed silhouette... one object with holes...

Of course the first thing you should do is put your art on its own layer and lock this.....for a complicated or hires raster image i would palette reduce the image first in your paint program of choice (i use paint shop pro)... this will save you allot of trouble when creating your vector shapes as this initial reduction will take allot of the guess work out... and leave you with an image allot easier to manually trace....

for more complex tracings....
i often then put another layer ontop of this and call it "Veil" or something like that... for this i just make one white rectangle bigger than the entire project and then make it 50% transparent....
This helps when your trace is half done to flick this layer off and on to see where your up to.

Then i would create a layer called main for completed stuff and 2 working layers above this...

I sometimes also create a backdrop layer if white is going to be distracting so i can preview my work as i go on a backdrop closer to the actual colour.

its important that you do employ overlap... as if you decide to blur or feather anything or even make some manual adjustments... producing a design in such a way that is has little or no overlap would be a blunder.

one approach is to block in large areas first and fill in the piece (block it in).
Then overlay the smaller shapes....

another approach is to start with the highlights and then progressively work down (top down)....
or a combination of these 2 ...you'll work it out good luck....