First off, some cold, hard facts...
Mithril Halls is a very harsh hometown. Coin and equipment are difficult to attain, at any level. Take a wrong turn and you go from rats and beetles to lamias in a blink. The distance to other cities is a huge trek for low levels. And! It is a dwarf only community, so if you die down there and no other dwarves are on... pray, pray hard.
Trades are great aspects to any character and have many uses to any class, but leveling them requires dedication. I'm talking hundreds of hours type of dedication.
Dwarves cannot be half-hearted. Unlike a race like humans, a half-hearted dwarf comes off as a short human with a odd accent and other players can tell. If you are thinking of starting a dwarf, find your inner dwarf and let him/her out!
Now that I have depressed you a bit, on to the good stuff!
1. READ THE RACE HELP FILES! Seriously, they are so very useful to anyone curious about being a dwarf. A lot of work went into them and they are worth the read.
(edit) Also read through Lysha's thread:
viewtopic.php?f=73&t=10117
2. Accent. There is a command in-game called 'accent', type 'help accent' next time you are in-game and read up. This is a built in system that translates anything you type into a dwarven accent. It is a wonderful system for anyone not comfortable with the dwarven accent or those that do not hassle with it. There is nothing wrong with using this system over making your own accent. I highly recommend this system for anyone starting a dwarf.
That said, if you are comfortable with your skills enough to do your own accent without the accent filter, personalize it. Take Gilain for example. A regular traveler and merchant, he is often in the presence of non-dwarves. His accent is a shifting mix of common and dwarven terms, a blend of his influences. Take a look at what your dwarf does and who he/she will be around often and adjust your accent to fit your dwarf. Don't discount the accent filter, personal accents are only recommended for experienced RPers, comfortable with their skills in RP and typing.
3. Watch other dwarves, not just in-game, for tips. I commonly mention the dwarf, Gimli, from the Lord of the Rings movies. Watch him during the films. How he distrusts (not hates!) non-dwarves, especially during the first film ("Never trust an elf!"). How he reacts when Frodo shows his mithril shirt the first time, the awe and reverence. His uneasy and inexperience riding a horse in the second film. Pride in dwarven work, such as how he describes his cousin's kingdom, Moria. His pride in general, ("No one tosses a dwarf!"). His reaction to anyone questioning dwarven strength. The reaction to orcs and other enemies, especially while in Moria. The love of battle, even going so far as having a kill count competition with his companions. Use of tactics one moment and rushing into battle the next. Dedication, loyalty, and self-sacrifice for those he considers friends. His accent, heavy but understandable.
4. Read up on trade help files, if you plan go into trades. Familiarize yourself with what weapons/armor you can make and how many ingots they take. Ask experienced miners about different metals and their uses. A ingot has more uses than arrowheads, learn them.
5. Languages. Learn common as soon as possible. Seriously, look around. How many NPCs can understand dwarven? Besides that, how many players do? Get common as quick as possible, practice it, and you'll have a much easier time.
6. Weapons. Whatever your main weapon is, if you can learn to use your mining pick, do so. Nothing is more annoying than being jumped while mining and having to switch weapons to something you can use effectively.
7. Memorize the Halls, or at least use a note pad to take notes. Where is the door out/in? Which tunnel was rats and which had lamias? Where was the healer? How do you open door XXX? Really, MH is a confusing little town and a few notes makes a difference. And read room descriptions, some of that is life-or-death important to lowbies!
8. Finally, enjoy yourself. It is a dwarf, not a career choice. Have fun with it! If you cannot take a day off and wear a dress, you are taking things too serious!
Anything to add, anything to ask, please do so. I want to tear down that wall of fear and confusion some have built around starting a dwarf.
I may even bust a few of my dwarvsies out now.