Like everyone has mentioned, there are two types of endorsements(actually three). Ones directly with the manufacturer such as Ibanez, ESP, Jackson and Caparison and there are the ones that are with your local Distributor and dealer (technically they're different but quite similar in what you get).
In the highly likely event that you don't get a manufacturer endorsement, the next best would be with the distributor of that brand where you have a much better chance *and* also opens the doors to OTHER brands that might endorse you since the distributor might do. They usually give you better exposure than local dealer endorsements because distributors are the ones that arrange the workshops, seminars, shows and clinics. That and since it's at the distributor level you usually get stuff at a price similar to a dealer, which is pretty sweet.
The ones with your local dealer is where you have the HIGHEST opportunity to get endorsed. Usually with these deals you promote/endorse the store and NOT the brands. The good things about this type of endorsement is that you don't have to get stuck with one particular brand of thing (ie. guitars, strings, etc..) since the endorsement is generally not brand specific unless the shop has it's one line of stuff. These types of deals generally get you better discounts on gear in general but in pretty much every single case the deals are not as good as if you were endorsed by the distributor. Band/Artist exposure is very minimal as all you might get is maybe your bands flyer on thier wall, but it's definitely a great way to start.
Personally, I have a lot of experience doing stuff at the dealer/distributor level NOT as an artist looking for an endorsement but as the guy who's doing the endorsing (I run a shop and I'm also the Canadian distributor for Caparison guitars). My suggestion is to try for everything but *make sure you have an artist/band promo package*. If you got any questions about what dealers and distributors look for in an endorsement, feel free to ask.
Note: believe it or not companies don't care too much how well you play. What you need to sell them on is how much more exposure or sales they'd get from endorsing you.