When starting a new game, one of the most important decisions you'll have to make is your starting race. Your race will determine what units you can produce and what buildings are available. While you can conquer cities of other races, this is the only one you're guaranteed to have, so think carefully.
For your first game, you might want to start with the orcs. This is the default race, since they have no special benefits or limitations and can build all buildings. Play a game and make a note of what tactics you prefer. This will guide you in selecting a race more in tune with your preferences. Note also the foreign cities you conquer and see if any of those suit you better. That may be the race you should go with.
Some races are clearly better than others and some suit only specific play-styles. Some are so restricted that they're really only suited for an experienced player who wants a challenge.
On arcanum, the "best" races are:
- Halflings - for their superior farmers and good ranged units and tolerance with other races
- High Men - for Paladins and few building limitations
- High Elves - For Longbowmen and power production
- Nomads - For Horsebowmen and Griffins
- Beastmen - For flexibility
- Dark Elves - For Warlocks
- Draconians - For flying ability
One of the factors in choosing your race is the special units you'll have available. Some units are truly game changing, such as Longbowmen, Warlocks and Paladins. Others have interesting special abilities than make them well suited to certain tactics. Take a look at each race and see if anything looks enticing.
Except for Orcs, all races have some building limitations. Since the buildings follow a kind of tech tree, the loss of one early building can eliminate the higher tiers. Pay special attention to the economic and religious buildings since, later in the game, money and happiness can become an issue.
If your people are unhappy, they cannot produce new units and if you are short on cash, you cannot maintain your army. This can have a snow-ball effect that can leave you wide-open to attack.