resources - What are some strategies for developing basic writing skills? Beginning Writing (again)

I have a friend who is going back to college after a decade, and is quickly finding out that his/her writing skills are not up to snuff. He/she writes in a style suited more for Facebook than business or academia. What are some strategies they should follow to start developing basic writing skills? I don't know that throwing them a copy of On Writing Well is the best way to get them started.

Edit: Adding to the question, any useful resources on organizing thoughts/brainstorming/mindmapping/outlining in advance of writing??