The only blush brush I have is a small 187. What will be the best for these blushes?
If you have small cheeks like me, I mostly use 188, if I want it mostly on the apples or 131, if I want a sweep of color across the cheekbones, retro disco style (they need to bring that baby back - it's so versatile). I've also got a mini 129 and 168 from some old, old sets that are just the right size for me, while the full sized versions are a bit too big, but I use them much less with brights. I like the 190 for my bright Cremeblend blushes, although some people would say 130 or bust.
Another thing with the bright blushes I've found....they often look really good when you just dab them on the apples of the cheeks - just enough to be concentrated around the apple, but not so much that when you blend it back towards the ear that you get much more color spreading out. Use a little bronzer for the cheekbone ridge back towards the ear if you need more depth or feel too pale. This is a great look with bright blushes that doesn't enter the clown zone.
Another trick I got from watching way way way too many old 40's and 50's Technicolor movie extravaganzas (where all the blush is super bright!!) is to place it horizontally much higher or lower than the center of the apples/cheekbones and then blending straight up or down from there. Higher for if you want a cute, girlish look or lower if you want more drama.
A dab over the bridge of the nose can balance any type of bright blush on the cheeks out a bit, for the sun-kissed effect. This is a perfect finishing touch, but be careful about using it if you are going for a very strong eye or lip too....'might be too much in that case and you'd just come off looking like Rudolph the Red Nosed Reindeer.