Do not expect immediate responses. Many users "idle" leaving their irc client online for extended periods of time. We're talking weeks of being connected. A user may simply be afk, at work, sleeping or doing stuff IRL. Be patient and stay online to wait for a response.
Please, immediately stop using a web-based client such as mibbit as they tend to frequently disconnect you. Get a desktop client, such as mIRC, hexchat, irssi etc..
Pay attention to whomever has operator or halfop status. Especially when they use keywords like "stop" or "warning."
If you don't want others impersonating you by taking your nickname, register it with "/msg nickserv help" without quotes
Do not abuse whois to follow people into every channel they're in. Stalker-like behavior is a quick way to get on the network staff's radar.
Many users keep logs of the chat. Only in channels specifically prohibiting logs or private messages is there an expectation of privacy.
If you want to get someone's attention, "highlight" them by typing their nick exactly as it appears in the userlist. Also called a "ding" because many clients make that sound when you are highlighted.
Guide for noobs
To the right is the userlist. In general the higher up on the list they are the more authority they hold. There are a few groups that these statuses are organized as. In order of highest to lowest rank:
i. Admin, usually owns the channel
ii. Operator, the highest moderator
iii. Half-Operator, can still moderate but can be overruled by Op
iv. Voice, the ops just like you. You get the privilege of speaking if it's decided that the channel will go into lockdown (channel mode "+m") while everyone else can't do anything.
a. A channel is a room you join. Such as #coding or #music.
b. A server is where users reside so that they can join a channel. Users in the same channel can actually be on different servers.
c. A network is a collection of servers such as irc.efnet.net or irc.rizon.net. This is where the channel resides. If you are having trouble connecting to some channel on a network because you're having problems connecting to the network at all, try a different server.
d. When a server goes down you may see a lot of users in your channels instantly quit. This is a netsplit. Do not panic; they'll be back shortly.
a. Join more than one channel at a time by typing "/join #channelname" without quotes.
b. Do actions by typing "/me yourmessagehere" without quotes.
c. Send a private message to a user by typing "/msg username yourmessagehere" without quotes.
d. Change your displayed name, your nick, by typing "/nick yournewnickhere" without quotes.
Most irc clients may automatically set users as being away after a period of time. Some even display this status with some icon besides their name. If not, you can usually mouse hover/right click a name in the userlist to see if they're away.
If inputting your password for nickserv or entering a passworded private channel, input these lines in the server window. If you accidentally type " /msg nickserv identify IAmTheBestUser hunter2" (a white-space as the first character) everyone will see it.
If you get a desktop client you can usually set it up to automatically join your favorite networks and channels on startup. Same for automatically identifying your nick.
Sometimes ops will kick a user from the channel as a joke. Try rejoining immediately to see if they weren't serious.
Highlight perfectly each time by typing the first or first two letters of someone's nick and then pressing tab until the right nick comes up. Tabcomplete will simplify your life.