I don't usually bother to make my own meat sauce I just use a can of bolognaise sauce with meat (there are a couple of brands available). Sounds dodgy but it's not. My mum always made it that way & everyone loves her lasagne more than anyone who does it the hard way.

The best ever bechamel sauce recipe I got off the back of a Rinoldi lasagne sheets pack:
60g butter
1/3 cup plain flour
3 cups milk
1 cup shredded tasy cheese
salt & pepper to taste
(it also suggests 1/4 cup of paremesan cheese but I don't use it)

Melt butter, add flour cook for 1 min. Add milk, stirring until thickened. Add remaining ingredients stir until cheese melts.

The white sauce is quite sloppy but it makes the best lasagne.