In the last year I came across the lectures of Steve Lawson on Youtube on expository preaching. They have been a very useful training tool. I highly recommend them for anyone who is preaching, but has not had formal training, or for anyone desiring to start preaching.
The first lecture I recommend by Steve Lawson is called, 'How we ought to preach.'
If you want to learn how to preach the Psalms, I also recommend Steve Lawson's series on expository preaching of the Psalms.
May God bless you
David Kidd www.churchofgodslove.com