Which class and race to play is, in general, a matter of personal taste, as they all have their strengths and weaknesses. In general, fighters are the easiest to play, followed by clerics, magic-users and thieves. Similarly, humans are probably the easiest race to play, followed by elves, dwarves and halflings. Note that elves can be multi-classed; if you choose to be an elf, you can also choose to be a fighter/magic-user or magic-user/thief. Playing a multi-class hero does provide for more up-front abilities in the game, but it also doubles the time it takes to gain new levels.