we are a tiny company and we get a shit tonne of requests. But I remember being in your position so here are some tips;
1) put the effort in- a team manager won't bother putting the effort in to read it unless you put the effort in to write it. SPELL CHECK SPELL CHECK SPELL CHECK!
2) it really helps to show that you love the product/ brand before asking for free shit- the majority of our sponno requests are kids telling me they love our stuff but don't already wear it... how do they know they love it if they don't already use it? Basically you've got to be a brand advocate before getting free shit.
3) make the edit short- no crashes. Just your best shit so far.
4) be succinct about your plans. Is a company willing to spend a dime on a 16 year old because they love it? if you have seasonal goals and plans that you can clearly outline e.g. i will be shooting with this film crew over these dates then doing these comps etc. A company will be more willing to invest in a young ripper if they're dedicated and have a plan.
I hope this helps and that i didn't come across as too salty.
Always just ski for yourself and have a good time!