Some "natural spices" are known irritants to the skin. Not everybody's skin, but some. Cinnamon is one of them.
I like using pop mica's for colour, because they give you the colour that you want (except for strawberry, it goes orange), and Liquid Brites for CP, they are easy to use. I think you have them as Lab Colours over there.
Oxides and ultramarines can take a bit of getting used to, and everybody has a different way of using them, mixing with water or oil before adding at trace. I have ultramarine pink and no matter how i use it I always end up with a greyish purple. Go figure.
Clays can add wonderful colour to soap, at the same time as adding the lovely properties of the clay. Rose clay will give the soap a lovely dusky pink colour, there are other colours of clay like green, blue, yellow, white.
When I first started messing around with colours, I used melted crayons. I wouldn't recommend doing this if you are going to sell your soap because that would be a labelling nightmare, and I definitely thing proper soap colours are far superior, but it gave me some colour to play with while I was waiting for my soap colours to come. I used crayola brand crayons which are made out of stearic acid, which some people add to their soap anyway, so I figured they couldn't be that bad. I didn't have any reaction to them in any way. I have also heard of people using candle dye chips. I don't know what they are made out of so can't help there.
I guess it all depends on what type of colour and effect you are trying to achieve.