Negotiating good price - buying & purchasing used/new tips advice

[Elvis 3.0]

I did a quick search and surprisingly did not come up with much. I am certain there has to be some info on here somewhere maybe I just didn't find it. Anyway, with all of the opinions on the forum I figured I would post to get a few tips on the process of negotiating a fair process from a dealer when buying either used or new.

I.e. how to haggle with the dealer regarding your trade and everything else...

-do you give a firm number of what you will pay and then allow the dealer to add on 'freight', 'processing', etc...?

-is the dealer playing tricks if the deduct the value of the trade before or after/ and how do they calculate your trade v. how do you calculate your trade, etc... and what is fair?

-what are some proven tactics in general?

-what to watch out for?

-what to do and not do....

any help would be appreciated.