Some small bits of advice when working with green stuff.
Use Vaseline, or some kind of oil to keep your
GS tool lubricated so the
GS does not stick to it (Saliva works well too as well as the natural skin oils from your nose/face).
If you're modeling a small piece it can help to put a tiny spot of superglue to stick the
GS in place.
You can change the mix of blue/yellow to whatever suits your needs. more yellow tends to make the putty softer to work with. this can have advantages when working on flat surfaces but will be more affected by gravity (drooping) I think it also takes longer to cure and will cure softer (so good for twisting into ropes which you can later bend and attach at will.
More blue makes it much stickier and firmer to work with which can be good if you're doing smaller or protruding details as it will be less likely to lose shape.
You can also sculpt the
GS into the general shape of what you're wanting, let it cure for 20min or so, and come back to it where it will be more resistant to your sculpting and allows for sharper corners, details, and edges.
As for what tools to use is completely up to you.
My favourite
GS tool is a small metal thingie from a manicure set. I think it's to treat your cuticles or something.
My other tools are my xacto knife and a small set of interchangeable heads of various shapes that fit into a pin vice (this I got from some card making webstore)
Hope this helps you out in the future. Enjoy working with
GS