I do this kind of work for a living here in NY and here is a little insight I can give you:
There are two types of ticket prosecution, the police prosecute their own tickets, or there is an ADA who prosecutes the tickets.
If you are in the jurisdiction where the police prosecute their own tickets the first thing you should do when you walk in is try and see if the officer who gave you the ticket is there. If he doesn't show up, you can ask the judge for it to be dismissed, the best case is he/she dismisses it - the worst is he/she give you another date (which if the officer misses again it gets dismissed).
I find that in jusrisdictions where the police prosecute their own tickets they are unwilling to "make a deal", and if they do it is usually not as good a deal you would have gotten as with an attorney. There are some places where the officer actually be willing to make a deal do that he still makes his nonexistant quota on convictions, but those counties are rarer. Most times you can outright say to the judge I am willing to plead to a lesser charge in the interest of speeding up the administration of justice and he'll either negotiate with you personally (sometimes he just tells you the lesser charge and you say yes or no) or sometimes oversee while you and the officer talk.
In areas where the tickets are prosecuted by an ADA, you usually have one or two people in charge of several departments worth of tickets so their more motivated to make a deal. Usually you will meet with them before going before the judge specificaly to make a deal...they want you in and out and your wallet open. In this case becareful of the charges they offer you, some lesse no points moving violations still have insurance penalties. Seatbelt violations and stop sign/traffic signal related violations are two that your insurance company looks for (and yes they pull your driving record yearly). I always shoot for a "unsafe door opening" which is pretty cheap and no points and the ins companys don't pay much attention to it. Seat belt and Cell phone tickets most jurisdictions won't negotiate so if you get one of those you may be better off paying it (although I can't speak for every county in the US). There are some counties where you will see the judge first before negotiation (this is to cull in the people who have been waiting for 3 hours and just want to plead guilty to get the fuck out of there). As before, let the judge know you would be willing to plea to a lesser charge and you may get what you want.
By the way, always be nice, friendly, and have a smile on your face at all times. Avoid making accusatory statements and try to be polite and relaxed. Judges at this level (as well as officers and ADA) have a shit job and are used to everything from insults to conspiracy theories hurled at them, if you are nice and friendly they are more willing to cut you a break because so few people are (this doesn't mean you have to grovel - they hate that too).
If your state has a deal where you take a class and it removes points, do it the insurance companies love to see that and won't automatically jack up your rates.
For those living in the NYC/ LI area here is some advice:
Don't bother fighting in Manhattan, they are the kings of drity play with speeding and parking tickets and it is extremely rare that someone wins (unless you have a lot of them). If you just have one ticket and earn more than $10 an hour you might want to consider just paying it.
Queens/brooklyn/bronx you can try but it all depends on the day and the court. I don't see a very good success rate for people fighting their tickets here either but your odds are a little better than manhattan. Brooklyn tends to be the worst out of the three for you winning
Nassau County - Fight it. Always. They negotiate everything but cellphones and seatbelts (the roadblock tickets). If you get out of date inspection violations, get the inspection within 24-48 hours and they will throw it out. Becareful though that your officer did not write you a misdemeanor, as you can end up in hempstead criminal court and it is a lot harder to win there and you will need an attorney.
Suffolk County - NAZI's. Every stinking one. I can't think of a single person that has won that wasn't based on the officer not showing up, and they reschedule three times before dismissing. Seriously the worst county to get a ticket in and even worse to fight it (they get a large chunk of revenue from this and guard it like it was gold). The court is also in the middle of freakin nowhere. It also sucks up a few hours to be there. If you make more than $10 an hour it is seriously not worth your time to come back 3 times on the chance you will beat it. One way I have found that helps is to make friends with a suffolk county officer or even better a volunteer fireman, usually they know what officers have been transferred or retired plus all the dirt in their lives so you can find out ahead of time if your officer is going to show.
there I have given away all my secrets.