All good advise, just remember when you heat the plastic it will go from milk consistency to thick glue like consistency then to a syrup that is when it is ready, if you can afford it you should get an infrared thermometer it will help a great deal with heating the plastic. I would purchase colors that are ready right out of the bottle i.e. watermelon, green pumpkin, junebug, black and the like, learning to mix colors can use up quite a bit of plastic during the learning curve, Keep it simple in the beginning and you won't be disappointed then prepare to open your wallet cause once you catch the bug its all over ..
Also when you buy your pyrex cup root through the cups as they are not made equal, some will have a narrower spout and thats what you want to start out with it will help in pouring a narrow stream and start out with 4ozs instead of 8, a half full cup is much easier to pour from than a full one.