I am a hobby pourer, so, for me, a microwave works best.
Just take your time, heat it a minute at a time until you get close to the 350 degree conversion temperature, and then do small time intervals until you get it the right temp.
I use a wire coat hanger, bent double, to stir my plastic, which seems to cut down on stirring bubbles.
Buy a digital thermometer, so you can check the plastic's temp. as you heat it. Once it starts to read 325 or more on the surface, and it has become more clear and runny, stir it, because the plastic heats from the center out, so it will be hotter than the surface reads. You don't want to heat it much past 350 overall, or you can scorch the plastic, which makes it yellow and useless.
I always add a little heat stabilizer (1/2tsp to 4 oz of plastic) because I do lots of reheats, and that keeps the plastic from yellowing.
If you mess up a batch, toss it, and learn what not to do from your mistake, but don't get discouraged. We've all thrown away our share of plastic.
Once you've begun pouring, let us know how you do, and do ask questions. Everything I know about pouring soft plastics I learned here, from members who shared their knowledge.