I took several attempts to master Béchamel.
I use 2 heavy stainless saucepans with clad copper bottoms.
A wooden spoon and a stainless whisk.
I scald whole milk first. IDK where I got the recipe but I add cold milk and 1/4 medium yellow onion with a bay leaf pinned to with a whole clove and a pinch of nutmeg. I let the milk simmer on a low heat until it starts to rise in the pan. I strain the milk through a fine mesh sieve lined with a coffee filter. I don't want any bits of nutmeg or milk skin in the sauce. In the other pan I melt my butter - just melt it - then start adding an equal amount of all purpose flour. Stir constantly with a wooden spoon until the raw flour smell dissipates.
That is where I always had a problem. I have an electric range and temperature control is a pain. The heat was either too low and my sauce tasted like flour or it was too high and the roux started to brown. I have learned to move my pot off and on the heat.
From there just slowly add the hot, scalded milk, whisking gently until you get that lovely silky texture.
I like fresh ground black pepper. Sauce purest use white pepper because they do not want the black bits in their beautiful white sauce.
When learning to make sauces I frequently had to make it several times before I got it right. Once I achieve the desired result it is never a problem to replicate.