Most of the basics are easily accessible via help menu (I personally like "Help Suicide" but in your case you should type "Help newbie"), but I'll go ahead and list a few that might not be so easily viewed.
Directions are north, south, east, west, up, and down. Type in "autoexit" to toggle whether the game will show you which exits are available on every move.
"Brief" cuts the room description out whenever you move.
"List" brings up the shop list in stores.
"Survey" is used in the wilderness, which'll show available landmarks within view.
To give items, it's "give <item> <monster/player>"
"Aq" brings up the autoquest info, which'll come into play later.
"recall" brings you to medievia town square. It's only available at level 16 or below.
"haven" brings you to the Newbie Haven, I forget at which level you lose access to it.
"score level" or "sc l" brings up how much XP you need.
The attributes (Strength, intelligence, etc) are important when leveling up. Con determines HP gain when leveling, Wis determines MP gain and training session gain. Make sure these are as high as they can go whenever you're near leveling (Max is 18). Int determines how many practices are used per training session.
"practice" brings up which skills are available for you to practice/use.
"weather" brings up the weather screen. Spellcasters should be especially wary of firestorms which block spellcasting.
I suggest you use this simple prompt (Your HP/MP/movement/stat/whatever bar):
type "prompt #w&k<#x&h#b/&Hhp #x&m#b/&Mm #x&v#b/&V&umv #x&b#b&ubr #w&X#bxp #x&Rr#w" which is easily readable by newbies.
Containers that are "held" do not count towards your carry limit.
If you're carrying a lot of items and need to find a particular one, type "locate <item>"
Type in "setcomm" to see what communication channels are available to you.
If you switch equipment a lot, set an item mode. Once you have your items set, type in mode <whatever> lock. To switch back to that item mode, type in mode <whatever>
Strength in numbers people, type in follow <whomever> to join their "formation".
Type in "form" to see your location in your formation.
Leaders can change formation position by typing in "reform <player> <position>" type in "reform" to see which positions are available.
Formations also have formtalk, available by typing "f <message>" Formtalk can span multiple rooms as can only be seen by formation members.
Type in "report" to say your current hp/mp etc.
Type in "freport" (Form report) to see the stats of your members.
The leader may elect a new leader by typing "Leader <player>"
You may leave a formation by typing "Unform <Your name>", leaders can also boot people like this.
Formation location is important, characters in the front take the brunt of the damage (Tanks), characters in the middle take have a reduced chance of being attacked in a round, but can only attack in melee if equipped with a weapon with the "Long" attribute, characters in the back row are almost impossible to be targeted, but can only cast spells or fire ranged weapons (bows, crossbows, etc).
"Rest" helps regen mana and some health. "Sleep" increases it, but leaves you unable to wake up for a minute or two.
If an earthquake hits, "REST" immediately, you'll fall and take damage if you try to move. On the plus side, earthquakes weaken monsters in the effect area.
"quaff" potions.
Important directions:
East, south, east brings you to the donation room. Pick up some free equipment there. "pull <itemname>" for more info on that item; it only works on donated items.
East, north, east takes you to the post office, "receive" your mail there.
West, north, west, brings you to the treasure store, sell your treasures there. (Bars of Aurellium for instance)
West, north, north brings you to the bank. "Deposit", "withdraw" or check your "balance" there.
Dragon crystals are special, read "help dragon crystal" for that.
Type in "player <player name>" too see the stats on that player. My name is "Zarikor" so you would type in "Player Zarikor" to see my stats.
Type "call" to call a dragon, it costs gold ("Call ?" to see how much), but you can easily "mount" it and "fly" to a zone of your choice.
There are emotes, read "Help emotes".
My personal favorite is nibbling on the cookie the size of a wagon wheel and GAR "pose"