For your main lead pot, i.e., on the stove or cooker, use an old heavy bottomed 1 pint sauce pan with a left hand lip. That way it will be easier to poor into bigger lead moulds. This size will be big enough for what you need and won't take so long to heat up.
Use small amounts of lead to start with, and always leave some lead in the pot when you've finished (easier to melt (start) with next time).
When you've melted the lead, scoop the "swarfe" "scum", off the top with a spoon to get to the fresh lead.
For your smaller leads use a small ladle, which you can just dip into the main pot, a lot easier and safer, pre heat first.!
Heat the moulds up first, do it on the side of the pot or the stove. The first cast of your leads without the loops, will confirm the heat of your mould.
Place your hot mould on a thick piece of wood to conserve heat,(not on the work top, the wife will throw a major fit and you and your leads will be homeless!) when casting. If your pot has a, i.e., plastic handle, etc, it may melt in time. You will have to replace it with a metal one (welded), or a thick wooden one. 
Filling the mould should be done slowly and steadily. This is not the time to scratch your nose or anything else that you may feel needs scratching (as us men normally do). If you're the type that is often overtaken by the irresistible urge to scratch strange places, find an understanding friend.
The lead chambers, then the pouring funnels will fill and the lead will rapidly solidify. Your first home grown lead have been formed. At this stage, if someone has talked you into using a plaster mould, be very careful. Plaster of paris retains moisture which, when heated, expands and may split or even explode the mould.
Now extract the wire using pliers, (if the wire is long enough put a crank handle shape in one end so the wire may be easily turned to loosen it). The mould will be very hot so hold it with a glove or rag or, better still, clamp it in your vice. Lastly, release the clamps, open the mould and bump out your first batch of leads. The solidified lead that filled the pouring funnels can be snipped off with side cutters after the leads have cooled.