Waldelfen taktiken
A wood elf team should first and foremost try to minimize contact with the opposing team. Your players are too fragile to withstand a smashmouth game of Blood Bowl. Instead, use your speed and agility wisely. Avoid tacklezones with your superior speed and dodge away from the players most likely to knock you over during the next turn. Keep in mind that your opponent can only throw one Blitz per turn, so if you can move all of your players out of their tacklezones, you can go a long ways towards reducing player losses.
You should always put pressure on the opposing team's ballcarrier. Your speed and agility should allow you to squeeze one or two of your players through the defensive line to blitz the ballcarrier. Kick the ball deep to ensure the opposing quarterback must waste half a turn (or more) moving backwards to get the ball. Remember that every player will fumble a pass or fail an attempt to pick up the ball at least 16% of the time. Make sure you have players in his backfield to capitalize on that. Your agility offers good chances for intercepting the ball, as well -- and if your opponent is aware of that, you can force him to take a risk or find a different receiver, one which is hopefully less of a scoring threat to you.
You should also be able to react to your opponent's strategies better. If your opponent pushes up one of the wide zones, almost all of your players can be in position to prevent him with only one turn's movement. Furthermore, you can give the impression -- by stacking one side of the pitch with the majority of your players -- that you'll be traveling up one wide zone, then use your speed to swing the other way and catch slower teams off-guard and out of position.
Dunkelelfen taktiken
On defense, put two linemen in his backfield early, compelling him to deal with the linemen or move the ball from a position of safety quickly. His cages will now need backs, you will have receivers to help capitalize on bobbled balls and the pressure will be on to keep the ball covered up. Forcing the play on his half of the pitch is another good possible outcome. Elves are adept at taking a ball on the pitch and converting it into a touchdown in the same turn. Make sure you have a safe place to hold the ball -- the opponent's endzone -- by putting a player in scoring position even on defense.
If possible, make sure your players don't end their movement in contact with opponents. Keeping your team alive might include dodging players one square away from opposing players and relying on the one blitz maximum to limit the amount of punishment your team endures. If your opponent is undermanned or under-strengthed, move in and keep contact. Make sure one opposing player is on his back each turn to receive a boot to the head.
From the opponent's endzone, count backward six squares. Mark that line in your mind as the Red Zone -- the place from which your players can score. When you receive, move players you want to develop into the red zone on turn one. If you only use one player, they'll get knocked over for sure. Use three instead. They'll be able to knock over one, put tackle zones on the rest but it will take five or more players away from the LoS if they want to do it right.
Get good at the Run-Pass-Run-Handoff-Run-Score routine. It's something elven teams do well. It will go nicely with the next tactic.
The Relay: Before picking up the ball, move a Witch Elf or a Blitzer with Dodge to midfield, behind the line of scrimmage, as the relay player. In the next turn, move your ball carrier up, quick pass to the relay player and have the relay player run and dodge to a point where the ball can be handed to the receiver. Rather than hand off to a receiver that's in a tackle zone or two, position the relay player in the path of the receiver as the receiver is moving to the endzone. If you can, use a blitzer to move one of the tackle zones off the receiver to clear his dodge path. The pass-handoff-score allows you to chose which players will be getting the TD (which aids team development), is safer and more accurate than longer passes and also prevents most interceptions.
For cards, choose a Magic Item each time. The Magic Items will help keep your team intact, featuring Healing Scrolls, Magic Helms and Magic Sponges. Take Random Events until you have a full roster and Dirty Tricks from there on out.
Team Development
Good team development rules apply: Get a kicker early to force the play deep in his end of the pitch. Give that kicker the Diving Tackle skill to keep opposing coaches honest about targeting him. (He'll still be targeted but the coach will need to put some effort into it.)
The Dark Elves don't have catchers. With their high agility, that's actually a good thing. It forces you to use others to catch and those others will get the TD SPP's rather than a corps of catchers.
Be the first coach in the league with a Dirty Player. Use him judiciously to take down opposing threats rather than booting any linemen and happens to be down. Protect your DP to make sure he's not KO'd or worse, leaving you with plenty of bob and weave but no punch. The game turns bad when it revolves around fouling but it's not wise to expect your opponent to be "gentlemanly" if he shows up with four guards and eight players with Mighty Blow. Put Diving Tackle on your DP early and then Pro. They'll get plenty of experience in short periods so make sure you have a retirement plan for over achieving (read "bloated") Dirty Players.
Tailor your skills to your league. Bring in Tackle for faster leagues and Dauntless for bruising groups. Don't put these skills on the same player. You'll begin to depend on him and will be lost when he's SI'd. With Doubles, choose Guard and Mighty Blow. After AG increases, choose Leap and Strip Ball.
For long-term development, elven teams that thrive are the ones that survive. If they can keep from getting pounded, they will be scoring threats and consequently game winners. Dark Elves have a decent AV but it will get chewed up against a team with mighty blow and strength. Putting defensive skills on players and limiting the damage you take is very important. Look for Dodge early, perhaps even before Block. Not only will it help you stay upright during blocks, it also increases your ability to successfully avoid your opponent's tackle zones. Remember -- he can only knock you down once per turn if you end your turn with all of your players outside of his tackle zones.
The start up team I'd choose depends on the maturity of the league. In a fresh league, I'd choose an Apothecary, a 2 rerolls, an 8 fan factor and 11 line elves. It's not skill heavy but with AG4, you can afford some gutsy die rolling in the first few games while your fan factor makes some money to afford the pricey players. With a mature league, I'd start with an Apothecary, 1 reroll, a 4 fan factor, a Passer and 11 line elves. You can rely on the mature teams to boost the gate but will need an extra player to deal with the brutality.
Never Apothecary a Badly Hurt or a pre-game Niggling injury. Never. Think twice before immediately healing a Serious Injury too. More times that not, a player getting seriously injured will only miss the next game. Chose carefully the players you'll apothecary for an SI. Save your apothecary for the Turn 8, second half death of your prized witch elf. It's not a question of whether it will happen. It's only a question of how bad you'll kick yourself for losing the killed player.