Important
LANGUAGE WHAT IS IMPORTANT
Write in full sentences, proper punctuation, no .... dots, no abbreviations, no street language, no local English terms (patwa, pidgin).
Typo's, wrong spelling and wrong grammar are unnecessary, there are tools for that.
Watch your syntax.
Make sure your message is a whole, smooth. Don't read a bit, react to that, read another bit and so on. That will lead to an incoherent collection of short sentences. Name the things your are talking about (not 'yes, I think so too' but 'yes, I also like that movie'). Otherwise the client needs to re-read his own messages to find out what you are actually referring to.
ATTITUDE HOW TO TREAT A CLIENT
Clients pay for this, they deserve a quality answer for their money.
If the client writes a long message, make an effort to somewhat match the length. Be nice, give the client the feeling you appreciate him. Don't just answer, ask questions as well. It shows you are interested. Don't just react to what he is telling, bring something to the conversation from your side too. Your profile should be just as alive and kicking as any other human being, not an answering machine. Besides the client is interested to get to know you too. You won't bond if you never tell anything about yourself.
Don't ask too many questions in one message. It is a conversation, not an interrogation. Don't be negative. Most clients already have a partner like that at home sitting on the couch, nagging. They don't need you to do the same, they are here to escape reality.
CONTENT HOW TO REACT TO A MESSAGE
Always react to the full content of the client's messages. Answer the questions and don't ignore things. That's rude. Not only in a paid chat, it is always rude.
Always use a 'call to action'. After all it is your job to make them react. The most common way is by asking a question, but there are other methods as well.
Don't put a question mark at the end of a sentnce making it look like a question while in fact it isn't. Don't use hanging questions (I have a secret, want to know what it is?) That is annoying for your colleagues.
Follow the line of conversation and if you ask questions, ask questions about the subject(s) of that conversation. People like to talk about things that keep them busy. If a client is asking about music, keep talking about that and keep asking questions about it, in stead of putting a cold question at the end of your message like 'where are you now?' This kills the subject.
Ask clear questions: not '...and how about you?', but '...and what kind of movies do you like?
RULES STANDARD RULES
MISUSE / ABUSE ABSOLUTE NO GO'S
To mention a few:
Don't be surprised to get fired by a company, if you don't obey these no go's. In case of real abuse with possible damage to the company, you will not get paid. Real copy paste, asking or sharing contact details, deliberately telling clients it is fake when there is no reason or renting/selling an account and/or letting other people work on it are a number of things that count as real abuse.
The above are just general rules for operators. Most companies will go by these, but there will be differences. Also there can be extended rules on how to answer specific type of messages, like pokes and triggers. So no matter the company you might be hired for, always ask them the latest version of their manual and make sure you read it well.