I use Premo clay. It stays warm and flexible for a long time.
I use it at a medium setting. Except my accent colors (black and white) which I like to make a bit thinner than the main color.
I suggest you use a layer of trans first. The size of the rectangle you are using. Then you need to decide what color flower, feather or leaf you are making. Then pick colors that compliment or contrast it.
Use the wedges to the right here. . .you can vary them any way you want. . .this is merely a small sample Then wedge in your colors. I personally put in layers of trans to separate my wedge layers. . .but it is not necessary. You can use trans and another color for your two wedge colors or use two colors. If you use a skinner blend layer you might not need a wedge at all.
They need to fit together like puzzle pieces. Cutting them together helps. I would not layer the wedges and alternative layers any higher than 6 or 7. You can try more. . .but it may be a learning experience. Now that you have all your layer made and stacked. . .scrunch the edges/corners a little. This is to prevent it from splaying when you put it in your pasta machine at the largest setting. Turn it over and do the other end through too. Now you have a longer and fairly thin stack of wedges. . .not quite a flower yet! Now you need to chop it into equal parts. . .cut it in half. . .in half again. . .in half again. . .you may want to do thirds at some point. . .your goal is to get a lot of pieces all the same size. This next part is the hardest. . .you master this. . .you rule! Starting at the start of the line of squares (it is important