I'll post it here too in case this would proove usefull to someone.
The goal will be to edit a non mvc base into something more mvc like. Can be usefull to give a fresh feeling to some edits, avoiding overused bases.
So we'll pick an horrible 3d char, let's say lina for angel eyes. Be ready it's going to hurt your eyes...
...
So this is Lina :

The pose is interesting, between that and the high heels, it would really fit poison ivy.
So let's make a poison ivy sprite.
The first step will be to recolor the sprite in a plain way, and give some concept to the hairs, nothing definitive tought... Note that we'll take care of the skin later.

>>>

Now, the most evident problem is the proportions. While the chest is not that far from mvc, the legs are far too much slim, and the arms could use a few fixes. So let's do that, just adding a few pixel there and there...

>>>

Okay, we now have our base. Let's outline a little and start to define the outfit (with a darker color of what is outlined) :

>>>

Now we need to add some shading to the outfit. Let's start with the legs. Pick the color used on the legs and make it a bit lighter. Now work with the shading style your the most confident with :

>>>

That's better but three shades is a minimum so let's add one more. Again pick the same color, lighter.

>>>

Let's do the same for the dark green parts of the outfit, but first we need to define these a little more. That would give something like that :

>>>

Good now let's add the two missing shades of dark green :

>>>

>>>

Right, only missing the skin part, gloves and hairs. Now is the time to recolor the skin, plain again.

>>>

Hum... The shoulder to the right seemed a bit weird, so let's cut the arm and bring it closer of the body. Redraw a little the arm and shoulder and let's finish the gloves while we're at it. I also started to define the head and better the neck and hairs.

>>>

That's better, now let's add the shading to the skin. Still the three shades rule (not counting the outline shade)

>>>

>>>

Now, all that is missing is some shading on the hairs. So let's do it :

>>>

>>>

Done ^^
So basically we went form this

to that

Hope this will prove usefull to someone.