The paints

The paints used for marbling fall mainly into two categories, watercolours/gouaches and acryllics. Acrylics are more often used today, as they are waterproof , and can be used to marble fabric. However, watercolours are simpler to use, and give a wider range of patterns .
 Some paints work better for marbling than others. For example, one paint may spread uncontrollabaly, another would refuse to spread at all, and some others may be very pale.
 Generaly, the best paints to use are artist's watercolours ( as opposed to student's watercolours), or gouaches ( Gouache is simply a opaque watercolour) . These paints give more consistent results, and are less likely to fade. Brands like Windsor & Newton's are of the highest quality, but are very expensive. The next best type would be Daler-Rowney's designer's gouache . This paint is quite cheap, and produces decent results.

 However, even within the same brand, diffrent pigments behave in very diffrent ways. Some spread like mad, and dominate the paper ( like phlatato blue), others are heavy and dense, refusing to spread  much. To make matters even more confusing, companies may change the paint formula, thus making a previously good paint useless.

To that end, I shall furnish you with a list of colours that have been known to work. The following list is but a guide, and more colours can be introduced to please the fancy

yellows
Yellow Ochere

Reds
 red earth
cadmium red
alizarin crimson

blues
prussian blue
phlatato blue
indigo
ultramarine

greens
A mixture of phlatato blue and yell. ochere
phlatato green

Black
lampblack,
ivory black
 note; a little prussian blue phlatato blue or indigo can be mixed into the black to make it denser
Brown
burnt umber
burnt ocher
umber

 Other colours, like orange and purple, can be created by mixing the appopriate colours.