Lemon Meringue Pie Tips Needed!?

Ideally everything should be cold, including the bowl and beaters. Cream of tartar is best for stabilizing the egg whites, never heard of using cornstarch. And when you put the meringue on, seal the edges of it to the crust. There should be no gaps at all. That prevents the 'weeping' that's commonly seen on meringue pies. Good luck, it is kind of a tricky pie.