I was wondering if anyone had any tips for add white markings to horses (I use IbisPaint) a general description is welcome

I will prep my horse completely first. I will normally have a layer with my shadows and a layer with me highlights. Under those two layers is where I draw my markings. I use a fairly off white/ pale greyish brown to do my markings. I then go back to my shadow and highlight layers and add, remove or fix what I already had to then suit the white markings. Lastly I'll either slightly smudge or erase the edges to make them softer. It takes a bit of practice and my explanation is probably very bad but I hope this helps!

Lasso tool the patterns. Then copy and paste into a new layer, so if you make a mistake you dont have to restart. Then turn brightness all the way up, and Contrast down a little. To preserve shadows, and detail. Then go to your Saturation tool and turn down the Saturation as much as you need to get the right look. The use your Curves tool, to get that ¨more natural¨ look. You can always adjust the brightness/contrast also. Then I smudge around the ¨hard¨ lines of the patters to make it look natural. Using a 3-5 size brush at a 90 strength, I just ¨swirl¨ the hard lines.