There basically are no 'wrong' or 'right' choices, as it all depends upon your playing style and your goals in the realm. The proposed newbie and expert choices are just meant to give you some ideas about certain strengths and weaknesses. The best way is to try several combinations by yourself, and find out what you like best.
Anything goes...as long as it gets approved by the gods ;)
Pick something that you can remember easily, preferably with numbers and characters. Make sure NOT to use your homebanking password.
Though there are rumors about secret abilities that are innate to one gender only of some races, gender choice has more social repercussions than gameplay ones.
Newbie choice: Human
Humans have evenly distributed attributes, avoiding some pitfalls like not hitting anything because of low intelligence.
Expert choice: Elf
Mana! Elves get an extra amount of it, making up for any initial problems, like sometimes not being able to wield their sword if they start as a warrior. The lower hp can easily be compensated with healing potions. One look at potion prices reveals why elves are the expert choice: 1 movement point costs about 5 gold, one hit point about 20 gold, one mana point about 300 gold!
Newbie choice: Warrior
As a warrior you can concentrate on exploring and learning the basic game commands, without worrying about complicated spell usage or dying after two hits because of low hp.
Expert choice: Thief
Thieves get a tough start: average hp, no spells, low damage. But once they learn knockout and backstab, they suddenly transform into the ultimate killers. Whether you prefer mob slaying or hunting other players, nothing beats a thief at killing quickly and efficiently.
Newbie choice: New Midgaard
Large enough to contain many shops, guilds and travel connections, but small enough not to get lost. Cheap healing potions too.
Expert choice: Atalia
Huge town, more shops than a troll can count, easy money, good guilds (though not for druids yet).
Newbie choice: No
There isn't much fun in starting from scratch each time you die. And you will die. A lot.
Expert choice: No
Unless you are masochistic or want to show off, there is no point going down the hard-core route, as there is no gameplay advantage at all to make up for permanent death.