Strategies

What strategies do you ask would I have to offer you? Well, although not a huge section... strategy as in being each race!
Elves- When being Elves, it is clearly a fact that you must get the largest town there is available, and upgrade to get the best units. Elves are not great fighters, and they highly rely on the slightly weak Unicorn and semi decent Nature Elemental. When all else fails, Nymphs are very important to seduce stronger perhaps neutral-evil units on your side.
Halflings- With Halflings, it is best to rely on their Pony Riders in the beginning of the game to scout, for they make decent fighters early in the game and are easy to produce. Despite this, their Leprechauns is the most DEFENSIVE unit in the game that can be produced in towns, with a great defense and resistance level of TEN. Best to produce many Leprechauns to win their battles later in the game.
Dwarves- Dwarves are best used as melee fighters, and most of their units have superior damage and attack rating compared to other units. Their most upgraded unit... the Dwarf First Born, is one of the best units on Age of Wonders. I would highly suggest you build many First Borns, your chances of success would increase very largely.
Highmen- Highmen get a very good unit early in the game after the first upgrade, which they are Paladins. Paladins although have weak defense, their attack is medium and are some of the best calvary in the game. The main reason however, why they are so cherished... is because every Paladin that is produced has Healing. So despite you being able to have many Paladins quite easily, I would recommend also producing a LOT of Valkyries and Astras to help your Paladins fight the forces of evil!
Humans- Humans are fun to be, for they also possess a mid level calvary unit in the early stages of gameplay. "Human Medium Calvary" are tough calvary believe it or not, who use pikes to stab their enemies. Not being able to overrun a group of Orc Calvary or Paladins, they can deal damage to many foot soldiers.
Azracs- Azracs is probably the second best race in the game, and they have a "HUGE" advantage in the first stages of the game. They can produce the "Elephant" which has an incredible 13 HP and "Wall Crushing" ability, though not fit to hold back the elite forces of other races Elephants can be a great barricade and also a spectacular offensive force. They also have one of the best fully upgraded units, the Yaka Avatar, whom is very powerful in stats and HP. Produce alot of Elephants, Djinn, and Yaka Avatars and you are almost guaranteed victory.
Lizardmen- From the slimiest lands and swammpy areas of the Valley... come the brutal and harsh Lizardmen! Lizardmen have a few good units, such as the Lurker and Frog Rider. Their best unit is the Basilisk, whom is among some of the best units in AoW. If you make a lot of Basilisks, they can swim all over the lands and rivers, conquering other towns from the water! Great unit... and a great race, for all the other Lizard units also swim!
Frostlings- Frostlings are first are very weak and dull, also their size diminishes their moving ability. But after a few town upgrades their units get slightly stronger, especially after gaining the mighty Yeti, and making LOTS of them. The Frost Queen is decent in ability, but her defense is too weak. Nordic Glows are the best scout type units in the game, for they fly and are FAST. Also, Ice Drakes are not as STRONG as their other dragonparts, but they still manage to serve the Frostlings well.
Dark Elves- The best race in the game, and many people do not believe it until they have played them just enough to see why... for they have great potential and ability. Dark Elves have no "super upgraded unit" such as the Lizards' Basilisk, Dwarves' First Born, and Azracs' Yaka Avatars. Their strongest unit is actually their Dark Elf Executioner, which has the best attribute in the game... Life Stealing. Their defense is semi weak, but their attack rating is high enough to be able to strike their enemies and damage is good actually for Calvary... they are the best calvary unit as well. Do not bother with Dark Elf Riders, they are not as good as Executioners, but another reason Dark Elves are the best race... their most upgraded unit is called "Incarnate" which has a huge amount of success <such as Nymphs and Lady of Pain's SEDUCE skill> of their POSSESS skill that they can enter the body of <ANY unit over than a leader> and most likely take full control. If the unit dies, the Incarnate rises from the dead body, only to take over the one who killed his last victim as well. Make Incarnates if you have a lot of tough enemies, and make a huge amount of Executioners... and another good thing about Dark Elves is that their BRAINS... they also have a good amount of success of keeping morale high when employing other evil races such as Orcs and the Undead to do their bidding. Imagine, the Incarnates, Executioners, AND Orcs and the Undead even Goblins on their side... an UNSTOPPABLE race.
Orcs- Orcs are tough and rough, they are more into melee and a bloody fight than the mighty Dwarves! It is considered an honor for them to hold a broad sword to swing "Chopping Blades". Even the beginning Orc Swordsmen packs a powerful punch, and the Orc Warlords... one of the most deadly units in the game. Warlords are not the highest upgraded unit, but their stats are very well balanced and have good HP. Also their skill is very special when surrounded and outnumbered, by using "Round Attack" he can basically slaughter all who dare to try to corner him!
Goblins- Goblins, the most disgusting like race and very filthy creatures. Their Goblin Spearmen have a good advantage in melee fighting, when defending they take the "First Strike" in battle and do make some decent warriors. Their goblin bombers are one of the most unusual and most deadly units in the whole game. If the bomb explodes, there will most likely be a huge amount of damage and destruction left. Karaghs are... as I've stated of other highest upgraded units before, Karags are one of the best units in the game. Their defense is very weak, but their attack accuracy and damage is HUGE, if not the MOST of any unit I have ever seen.
Undead- The Undead... the most evil out of all the races, stated as of the "Pure Evil" alignment, the Undead are deadly and every unit they produce is "Fearless" due to being already... dead, they have no fear of anything. Undead produce the almighty Reaper at the last upgrade level, which can "Invoke Death" which could be considered the best ATTACK attribute of all attributes. Invoke Death can work on ANY unit, even the Undead and Leaders. This means if Invoke Death is casted on a unit, and it worked, the unit is officially DEAD. Make alot of Reapers and you could have very quick victory in a matter of moments.
Those are the strategies on how to use the races, feel free to study all you need to know and check out the other sections such as the RACES section for more info about them. Good luck!