Dave - That was an uncommonly brief response for you.....
To expand on Stomm's comment a bit, Wayne is a fellow who goes by the name of Ullgityer on these boards but who doesn't seem to have posted anything in a while. He's been playing Orcs since the WM rules first came out and has mentored us all in Orc tactics over the years. Unfortunately, I can't seem to find any of his treatises on the subject just now. In a nutshell, though, since the maximum Command value in the Orc army is an 8, he recommends taking as many commanders as possible and creating a like number of brigades. This is done in the hope that you will be able to at least move something each turn and therefore be able to keep the attack going. He is also recommends maxing out on Shamans and is a great proponent of the Gerrroff! spell (that it, use it AS MUCH AS POSSIBLE).
Brigading Goblins with a Rock Lobber is a good idea as it will provide stand&shoot attacks that the Lobber itself doesn't have. This is especially useful early in the game since the only things that can usually get at the Lobber in the first 2-3 turns are Flyers. Goblins are also good second rank support troops for your Orc Warriors. Trolls are hard for the Orc army to use since the BEST command roll you're going to have for them is a 7. Still, they're a nice looking unit which it is hard to not want to use. If used, best to set them some somewhere that they may be able to charge on initiative later in the game - perhaps somewhere near the Lobber. For five points less, you may be better off with Ogres. The Giant is a really cool unit that can give your opponent fits (especially if your opponent is me!). Well worth the 150 point cost. Boar Riders are an excellent unit (as azrael points out) and, with their 4 attacks, Orc Warriors are pretty good as well. Black Orcs are one of the better infantry units in the game and are priced accordingly. It can be frustrating to watch them stand there and do nothing because you can't get them to move! I've not had much luck with Wolf Chariots either, but I keep running them out there because I like the way they look - plus, the concept of wolf chariots just appeals to me. Wolf Riders can be very useful for shooting at your opponents support troops, driving them out of support position.
When things go well, the Orc army can be really fun to use. When they go badly it makes for a quick game.
