Here is a guide how I painted the Soulsnare Shackles from the Malign Sorcery boxed set.
Step 1.
I started with priming the model black and added Astrogranite with a texture tool from Citadel.
Then I painted over the entire base with Mechanicus Standard Grey, covered the Astrogranite part with Celestra Grey, once the Celestra Grey had dried I mixed Lahmian Medium with Nighthaunt Gloom and applied three coats, followed by a light drybrush of Skink Blue.
Step 2.
I painted the chains and clamps with two coats of Leadbelcher while using a Basecoat brush, then tweo more coats of Ironbreaker with a Highlight brush and then a complete wash with Nuln Oil while being careful of pooling.
When the Nuln Oil had dried I re-applied three coats of Ironbreaker while leaving out the recesses and finally a a highlight of Runefang Steel, I focused the highlight on the top of the model as if the light source is coming from above.
Step 3.
I added some skulls from the Citadel Skulls box and used super glue to attach them to the base.
After all the skulls where in place I applied two coats of Zandri Dust, followed with two coats of Ushabti Bone mixed with some Lahmian Medium and then a careful wash of Agrax Earthshade.
When the Agrax had dried I reapplied Ushabti Bone to the skulls and then a highlight of Screaming Skull with Kolinsky Mastercall from The Army Painter.
Step 4.
I decided to add some rust to the shackles with Light Rust pigment from Forge World and using Pigment Binder to dilute the pigment in a pallet so I can paint it on, you can apply it one with a well used brush if you only want to the rust on the raised areas.
Finally I added some some lightly coloured tuft to create a little contrast with the base and the model.
Below are pictures of the finished models.
Remember that experience is the only thing that can not be taught.