I don't have much experience with it since I quite playing M:TG after I graduated from high school (save for a pick-up game here and there) but Magic Workstation might be a good place to start.

I enjoyed M:TG when I played it but it got to the point where I couldn't afford to spend money to expand my collection so I decided to quit playing. At the time I did play, I played two decks primarily:

A deck comprised almost entirely out of squirrel cards with the main goal of getting out an unsurmountable army of squirrels as fast as possible. I think the quickest game I won with this deck was in five or six turns.

The second deck was fairly solid but not as winning as my squirrel deck. It focused on elves and was primarily a defensive-focused deck with offensive capabilities. I gained life faster than most players could handle.

I never played tournament-style and the deck construction style that I used wasn't entirely free range (so tournament banned cards were fine to use) because it was with a large group of friends.