Admin asked me to comment on this thread (sorry I'm a little late with it).
First Attendance (FA) is not an alternative to choosing one of the options on your ticket. You must always request a trial. THEN you can negotiate a settlement at FA or before your trial.
FA is not offered in every jurisdiction and the ones that do offer it may not offer it for every charge (i.e. FA for speeding but not for parking tickets). Some places you have to schedule the FA, others you just go and line up.
Arriving early to your court date (at least 30 minutes in advance) you will be able to talk to the prosecutor in the court room to try and work out something. This is like an abbreviated FA meeting. This is usually less successful than a formal FA meeting as there is a time pressure to go through the docket before the justice walks into court. With a formal FA meeting you can take all the time you need. If not successful, you can always go back and hopefully get another prosecutor who is more willing to negotiate.
As for what to say, check out the sentencing part of my site: admission of guilty, a sincere apology, your driving behaviour has improved and your record is clean since the charge, there is little liklihood of you committing the offence again, the "societal interest" in convicting you is low, ...
One issue is whether to admit guilt or not. You can skirt around it a bit by taking responsibility for your actions and expressing a sincere desire to resolve the matter without truly admitting what you have done.
Or you can negotiate by saying you want to save the court time, it doesn't look like there is a strong case against you, let's settle this matter now.
There are different approaches to use depending on your situation and the vidence. That's why generally you should receive disclosure BEFORE you go to FA. Why negotiate a guilty plea if they do not have enough evidence to convict you in the first place?
With Red Light Camera tickets, the general rule of thumb is a 50% discount for a guilty plea (plus surcharge). As this is not a moving violation against a driver, it doesn't affect your demerit points or insurance. You can usually get this without any negotiating at all.