Attachments are another bone of contention, especialy users with slow connections do not appreciate image files being sent via e-mail, this can tie up their phone line for hours while the file downloads. Watch your spelling, use the spell checker if your e-mail software has it, remember that some words may be spelled differently in certain countries too. Read the message posted by the OPS when joining a channel, it is done for a reason and to inform new persons on channel of the channel rules and general topic. Some channels even ban on reporting of such behaviour. You will not be ridiculed for asking even the most silly sounding question on channel.
Experieced users are always glad to help the newbie.
Flooding the channel with a lot of text or scripts is also regarded as bad manners, some channels however are more open minded and even encourage it or specialise in this form of chatting. Hogging the channel by not giving other people a chance to say something is also very uncool. Try and type your message one line at a time or pause to let others catch your drift. This wil also give you time to read the other persons response. Just be yourself and consider other chatters as well before typing anything that may offend.