The best advise I have is pre warm the mold after cleanin it good , if ya don`t & have a small pot your gonna run out as it comes to temp.
Pour 2 cavitys until they cut easy then 2 more etc. even after pre warming .
Always have the sprue handle closed completely when pouring !
Turn ya heat down after it comes up to temp so it does`nt cook the tin off & cause voids, frosty is ok .
My recommendation is at least a 20# pot slam full of alloy .
Also I recommend just puttin the mold in a boiling pot of water for 10 min. to get all the machining lube from the pores of the aluminum . well most of it anyways .