These "rules" are especially true for big channels with dozens and hundreds of users.
Most channels insist on this rule. Don't ask if someone may help or is "there". Just ask your question (a greeting isn't wrong though) and be patient.
A very important one! If you ask a question you might get responses which are prefixed with your name:
[22:51:33] <soahccc> pls help
[22:53:23] <someguy> soahccc, what's the matter?
This is called highlighting and you propably will notice that the line is somehow different; it's highlighted. This is essential to follow conversations when there are more than one at a time.
You should highlight people if you are responding to them. You can highlight as many people as you want.
In order to highlight somebody you need to write his name all the time. To simplify that almost all IRC clients support tab completion which means that you only have to type in the beginning of the name and hit the tab key to autocomplete the nickname.
If you want help with something you most likely will have to provide some details so that anyone could possible help. When there is an error don't just say that there is one but instead post the error on pastie.org or gist.github.com and send us the link.
Depending on the channel you are in you should post your code or system environment information (like operating system, specs, software versions).
We can't see what you see so tell us!
To be continued...