• You can only deform an image that is on its own layer
• Always duplicate (Shft + D) the base nude and close the original--this way you never overwrite your original files and find yourself looking for them again online
• You can only use layers on an image that is 16-million colors (24-bit) so if you're unable to paste a layer or create a new layer check your color settings under Colors>Increase color depth  If 16-million is greyed-out (ghosted) then your problem is something else but invariably it will be that your image isn't in 16-million colors
• Sims skins will only show up if they are in 256-color (8-bit) mode.  Ctl + Shft + 3 will open a dialogue box with the options to decrease the colors to 256.  It will also bring up a warning about layers being merged if you proceed with the color decrease.  It's okay.  Just be sure to leave the image open after decreasing the colors if you plan to work on it more.
• When decreasing the colors to view my skin in SimShow or SimPose-ium I  hit Ctl + Shft + 3, okay the layer merge, okay the color decrease, save the file and Leave It Open.  Immediately after saving the file I hit Ctl + Z to undo the color decrease and bring back my layers so I can make more changes if necessary.
• The .psp file format will preserve your layers.  If you find you don't have time to finish a skin, save it in .psp format so that your layers will still be there when you re-open the file to edit it further

First thing's first.  You need the nude skin bases.  I have saved them in .jpg format so you start out with 16-million colors.  You can download them here.  When I am ready to make a new skin I open up the three skin tones for the body type I am going to use.  These are the steps I follow:

• Go to File>Browse (or hit Ctl + B) to bring up the image browser
• Go to the folder the base skins are kept in
• Select the three tones I am going to use by clicking on each one while holding down the Ctl key
• Right click and select Open
• Click on the title bar of an image to make it active then hit Shft + D to make a duplicate
• Repeat this step for the other two skin tones and close all the original images--this way you don't overwrite the originals

Now you've got your nude bases open.  I work on the light skin base because it's good for my shading cheat (which I'll delve into later in the tutorial).  Minimize the other two bases by clicking on the underscore in the upper right hand corner.

Now it's time to begin putting on the "clothes."  There are a couple ways to do this.  Either you start from scratch or you copy and paste outfits onto your base.  I'll discuss both methods for the sake of being thorough.  =o)  In my opinion the easiest clothes to copy and paste are those that are pictured on hangers or folded, rather than on models.

To keep this page to a minimum for download time I will put each method on it's own page.

You can find the copy and paste method here.
You can find the method which starts from scratch here.