Here's one way to make a 1000-point army, which involves buying only
four more blister packs in addition to the starter pack:

General (mandatory), 125
Hero w/Sword of Fate, 85
Wizard w/Dispel Scroll, 65
2x Crossbows (mandatory), 110
2x Halberds (mandatory), 90
4x Knights, 440
1x Cannon, 85

Total 1000 points.
Needed to buy: Starter set (US), Character pack, 3xKnights

The purpose of your infantry is to protect your cannon, and to stay
alive. The purpose of your cannon is to punish him at long range, 
forcing him to come to you; if he's in column you may kill stands as 
well. Your striking power is obviously the armored host of Imperial 
knights. Ideally, you've taken up position on or near a hill, so your 
cannon and infantry count as defended. Woods or villages will protect 
your infantry but you cannon cannot enter these terrains; nevertheless 
it is better that you lose guns, if necessary, than for your infantry 
base to be destroyed.

The wizard with the dispel scroll is needed because Orcs and Undead 
can really hurt you with magic, and they can pick on crucial units to 
do so. You don't want your knights to be suffering from Doom & 
Despair, or be slammed back by GEROFF!, on the turn you plan to 
launch your battle-winning counter-attack.

Dwarves are tough because their artillery is as good as yours; try to 
outflank them when they're on the flat, and never pit your infantry 
against theirs. Elves can go cavalry-heavy and, combined with their 
general's high LD, are capable of a first turn charge than can win a 
1000-point game - so be careful, try to deploy with an anchored flank, 
and support your shooters. Since Chaos can't shoot, they'll have to 
come at you.

Other methods of constructing Imperial armies include going long on 
infantry, especially halberdiers and flagellants, or taking a 
"shooty" army with crossbows, handguns, pistoliers, and steamtanks.

Most Imperial commanders won't take a Griffon until 2000+ points; most 
feel that the Steam Tank is not cost-effective; and most feel that the 
Hellblaster is woeful indeed.

Viel Glück!

Fürst Maximillan Ruprecht von Adlersburg