I know for a fact that when I started out customising and painting in the model horse hobby, the one thing you didn't want on your model horses was brushstrokes; the smoother the paintjob, the better as it looked more realistic. I also remember painting and on every model always getting them, and I became at my wits end when I struggled on what to do.
The biggest tip I can provide people with when it comes to painting in acrylics full stop is layers. This goes for base coats, facial markings, general white markings, appaloosa blankets and the like - anything with acrylics! Some people mention that paints need to be the consistency of 'milk'... Personally I feel that milk has the exact same consistency of water, especially the pasturised milk with hardly any fat in! As you can see, I dislike the term greatly... I tend to just say to water it down so it is thinner, but not so thin that the paint gets any paler and so it is almost separated. Lots of trial and error is needed and yes lots of layers will be needed but with the watered down paint, drying time is much quicker and it spreads in a much nicer fashion.
A couple of years ago, I trialled the use of a product called Maskol to see if I could get away with no longer using white paint for markings on my horses. I bought it off eBay.
Afterwards, once all of the paint has dried and you are happy, you start to peel the maskol layer. None of the other paintwork is affected.
I was still yet to peel off the maskol I had placed on the foot there...
This model was a commission to an almost mosaic pattern of bay and leopard spot appaloosa. I used maskol for this one to block out the main white areas. I really enjoyed customising this Breyer, it was a pretty big learning curve and the unusual colour makes her stand out!
I haven't used maskol for a while now, I tend to stick to painting using acrylics. But for all of those people who are willing to try something new, I would highly recommend it. I have no idea what it is like with pastels, but I am assuming it would work in the same way (although pastelling on it might prove somewhat difficult). My main tip if you were to do this and you wanted to use pastels would be to still use an acrylic basecoat. Having said that, if anyone tried this technique and uses pastels, let me know how it goes!
I hope this tip Tuesday proves useful!!