The trick with scoring regularly is to have a standard tactic that you can use, but also to be able to adapt to something completely different, depending on your opponent's defensive setup, and what he does in his first turn. In order to score consistantly, your offence also needs to have a good first turn. Suffer an early turnover, and it is too easy for your opponent to put pressure on you. With this in mind, the rule of "safe moves first" applies here more than usual. Basic ploys for the teams you mentioned:
Chaos are a
very difficult team to score with initially. Certainly until you have 4 CWs and/or a big guy. You just have to be on your game, take some risks and hope the dice work for you. Not a team to run if your confidence is low IMO.
Undead can play a slow grind like Dwarfs, or a quick running game like Skaven. For the former, the position of your Mummies and Wights is vital, as, unlike Dwarfs, you don't have linemen with
Block. For the latter, form a cage 3 or 4 squares into your opponent's half using Mummies and support, then burst a Ghoul out when in range of the endzone.
Dark Elves and
High Elves have similar strengths. Make as many of your players potential receivers. This will spread your opponent thin, and your natural AG should see you through. HEs often leave a thrower with the ball deep in their half, and get as many other players as possible into the opposing team's half. DEs obviously have the ability to roll a cage up a sidezone, using the threat of
Frenzy to create holes. I have seen both teams make good use of the "arrowhead" formation; 3 players in a line, with the middle one advanced one square. This is run deep into the opposing half, and hopefully the potential receivers can mutually support each other.
*This post may have been made without the use of a hat.