AnOrcishIncursion

If you feel comfortable with turn-based games, especially ones featuring units moving on a hex map, then you can play the Tutorial and then dive right into "Medium" to get a feel for the elements of the game. After you have played a few scenarios and are ready to hone your skills, try reading AdvancedTactics. You should also be familiar with the basics in WesnothManual -- this is a walkthrough, not an exposition of basic game mechanics.

Each scenario has an individual forum thread where you can provide feedback to the authors. You can find these here.

This is a simple 'Kill the enemy leader' scenario. The main objective in the first couple scenarios in this campaign is to develop your shaman line recruits, so you should recruit a fairly even mix of fighters, archers, and shamans. Normally as Rebels you would recruit many more fighters, but in this campaign you can be assured of lots of forest, so you don't need quite as many of them. As always, plan your starting recruits so that you can get the most villages quickly (many require a quick archer to reach expediently, unfortunately).

The battle is quickly over. Watch for the enemy Grunts as they have the highest damage dealing potential, and some Wolf Riders may try to steal your village. Try to milk the enemy leader for XP at the end, especially on your Shamans. If he's slowed, he's not much of a threat, even at night. Finish early for a nice bonus.

Assassins

Objectives: Defeat Ghalrsa, the enemy leader
Lose if: Erlornas dies or turns run out
Turns: 24
Starting units: Erlornas and another unit

Hopefully you're entering this scenario with a good hunk of XP on your units, if not level 2s already. Your primary goal is to get a Druid quickly in this scenario - the AI uses Orcish Assassins, which will poison you. A Druid will make this far less painful than if you were relying solely on your Shamans.

It is up to you where to make your stand, but try to get the enemy to fight from the river. Even if you lose a unit or two, the return damage he will deal hitting them in the river is quite tremendous and will greatly weaken their forces. Especially on the higher levels of difficulty, consider recruiting quite a bit more than one castleful for this scenario as the enemy will have units aplenty. This enemy leader isn't quite so easy to milk so finish it as quickly as possible.

Wasteland

Objectives: Defeat Gnargha, the Orcish Warlord
Lose if: Erlornas dies or turns run out
Turns: 24
Starting units: Erlornas and another unit

This is an interesting scenario - no villages. Check your income in the top: it's all you're going to get. The next scenario is possible with minimum starting gold but painful, especially if you don't have leveled troops that you're willing to lose. This is slightly offset by the gold bonus you will (hopefully) get at the end of the scenario. This scenario is as much an exercise in gold management as anything else. Keep in mind that some troops may level and try to stay under your income as much as possible with your upkeep. Multiple level 1s may be better than your leveled units in some cases. A Druid, of course, is a necessity with the lack of villages.

Establish your units in the middle "island" of forest. With some healers behind your line you should easily absorb the wave of attackers then take out the leader.

When you finish, you will get a small gold bonus that was laying around the orcish camp.

Valley of Trolls

Objectives: Defeat the two Troll leaders
Lose if: Erlornas dies or turns run out
Turns: 24
Starting units: Erlornas and another unit

Largely regarded as the first truly difficult scenario by many beginners, this has stumped many by either waves of Troll Whelps or truly scary adult Trolls, depending on your difficulty. What may not be obvious to you is that the troll AI has been set up to NOT USE the two mountain hexes that border their caves, but only the path through the middle. Once you realize this it is far easier to setup a nice bottleneck for them.

The troops from the shaman line should make good use of their slow attack. A slowed troll is much more survivable.

Good luck! Try to eliminate the blue troll quickly so that the teal one will be a sole target.

[stupidjaguar] I agree with all of the above. The scenario becomes much easier if you use the Sorceress line and Elornas, because of the Trolls' vulnerabilities to arcane damage. Slow them with Shamen and Druids, then take them out with faerie fire.

Linaera the Quick

Objectives: Defeat the enemy leaders
Lose if: Erlornas or Linaera die or turns run out
Turns: 24
Starting units: Erlornas, another unit, Linaera and three Mages

This is a fun scenario lending you a very handy unit, the Silver Mage. Be careful not to lose her and use her as a surprise attacker. The AI does not understand that a Silver Mage can appear from any of your villages, so when she's not teleporting around the map grabbing more villages for you keep her on a village so that she's handy to aid in a strike on an unsuspecting AI unit.

You may start off with low gold after last scenario, so start off slow, especially on higher difficulty levels. Let them come to you instead of you rushing them. You have plenty of time to take the rest of the map once the first wave has pummeled you.

A Detour Through the Swamp

Objectives: Defeat Keremal the Lich
Lose if: Erlornas or Linaera die or turns run out
Turns: 24
Starting units: Erlornas, Linaera and any surviving Mages

Pretty simple 'kill the enemy leader' scenario again. This campaign has a lot of them. Be careful of the undead at night - they pack a serious punch, but they're much less scary in the daytime. Your best unit will be your Mages. The final boss is a toughy. The only thing you really have that can hurt him is your Mages, with Linaera being by far the best as a Silver Mage (she resists the Lich attack quite a bit!). Get in a gang around him and then try to finish him off in one turn. If that fails, try again. You'll probably have heavy casualties finishing him if you're new to fighting Liches, and beware using melee attacks on him (he'll heal when he hits you), even if his ranged attack is truly terrifyingly powerful. Again, slowing the Lich will help a lot.

[comments by scorchgeek] Erlornas and Elvish Sorceresses also do heavy damage to undead. I sacrificed all my mages in the previous scenario and at first thought I would have to go back and repeat it, but as I had 2 Sorceresses, I did fine in the end.

Showdown

Objectives: Defeat the Orcish Sovereign
Lose if: Erlornas dies or turns run out
Turns: 24
Starting units: Erlornas, Linaera, another unit and 4 Elvish Rangers

Another kill the enemy leader, but with a twist: you get 4 loyal Rangers to sneak around the backside for an assassination! If you have any rangers of your own, send them along to and use the rest of your forces as a diversion to the southwest. If played well you can actually just destroy his army at the moment, but it's always fun to pop out of the trees and surround the bewildered AI.