Once a person is willing, where do you go from there? I think that the general recommendation from most is to start with the basic set up of the starting two teams of the Corporation and the Marauders, no ref and no cards. I agree with this... sometimes. Not matter what someone wants, I always play the first game with no cards and no ref, but beyond this, this is where you often have more success knowing if you are playing with a miniature gamer or not. If the person across from me is a mini gamer, then Corporation versus Marauders it is. They are probably intimately familiar with the idea of sides that are differently balanced but solid. These two will work with them easily. For the non-mini gamer, I really think the match should be the perfectly balanced Corporation vs Corporation. The truly balanced game is something much more similar to a board game. This, of course, requires you having 2 Corporation teams (preferably painted or with colored bases to help differentiate). After a game or two, then introduce the element of the Orx and Goblins.
***I would recommend that those teaching new players encourage them to watch the Dreadball Acemdemy on Beast of War too--it is a a great intro and a riot!***
The next step is the the introduction of the cards and ref. After a few games with the two starter teams and ref/cards, then I move on to talking about the Season 1 and Season 2 teams. Most people are ready at this point to begin a discussion of what they enjoy most about the game. This allows for a more seasoned player to recommend a team or two to the new player. I have found that the addition of the abilities slipping in with the new teams has not been an issue with new players. They are ready to soak up that knowledge happily. Sometimes it might require a few more minutes of explanation, but it's worth it. Adding just the rest of the Season 1 teams can also work, but after a few games, most people are either into Dreadball and ready to find their niche, or they appreciate learning a new game, but it is not for them.
After all the Season 1 and 2 teams are introduced, then MVPs in Exhibition Games are next. Which leads into introducing Season 3 and 4. This should lead into Exhibition Games 120 or 130 MC to use for Coaches and Cheerleaders and abilities rolled from charts. This should lead right into a league. Hopefully, you have a decent community or a good number of interested new players when a league starts. The more the merrier is definitely true for a DB League.
And as always, the key to it all is to have a blast!