I'm going to try to explain this in a way that even non-painters can relate. These are cheater roses. ..in no way meant to look like an actual rose....the same as fargo roses, spiders roses and other CQ roses...just enough to simulate a rose. Like CQ it just takes a little practice. You are not creating artistic wonders here just little buttons...Have fun!!
I like to also use a liner 5/0 (on the left), a long thin brush, an angular 10/0 (in the middle) and a pointed brush called a spotter 000 (on the right) If you're going to splurge on any one of these do it on the liner..
You can get by with just a spotter (tiny pointed brush used to make dots or spots hence name), even better a spotter and an angular.
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Paints: To start I'd recommend white, yellow, blue, dark and light green, dark pink or burgundy and a medium pink. I just buy inexpensive acrylics at the craft store and often find bags of them at thrift stores.
The final steps are to make several thin lines of pink, then white, then burgundy right over the eyebrow.
Brushes: Jerry's Artarama has a "mini" set of 4 brushes for $14.95. In fact they have many mini sets but this would be a good starter set at a good price.
http://www.jerrysartarama.com/art-supply/catalogs/0064481000000
Another online source for good prices is Cheap Joes at www.cheapjoes.com. The trouble with Cheap Joes is they have sooooooooo much stuff that unless you know what you're looking for it's very confusing and their site is not very helpful but prices are good.
Personally I just buy my brushes at Michaels (our local big chain craft store) I do not buy expensive brushes because they need to be replaced quite often.
Buttons: You can paint on any smooth surfaced button...glass, plastic etc. I prefer mother of pearl buttons. because I love their luminosity. 3/4 to 1" are the best size but 11/4-1 1/2" are the easiest to start with. I also prefer a little thicker button with a self shank or metal shank but they are difficult to find and often expensive. So I mostly use ones with holes and fill the holes with a white filler from the hardware store. See prep info below...
Some online sources include: 1" buttons and up $2.50 a dozen
http://buttons4u.com/Merchant2/merchant.mvc?
Also very large ones available at http://www.umei.com/buttons/mother-of-pearl-buttons-cat-bsp2001-6001.htm
and they are available on e-bay.
Roses look great painted on black buttons also....