Some ideas for the youngsters to help them attain some spots without asking or sending cds to promoters [which you can do if you like, just not my thing] :
Attend events
Enjoy the events you attend or don't go back :-)
Let it be known you would like to dj
Don't do it for the money
Play OVO if you intend to be an OVO dj
Create Podcasts and / or YouTube accounts posting tunes you love / would love to play out [good promoters in my experience know who they are booking ie have done their own homework]
Then when asked,
Turn up
Turn up from the start of the event to hear what's played and don't duplicate (if possible)
Be respectful to the "older" guys - you learn in time most of them know there stuff
Play what you love and don't buy for the floor (they may go hand in hand, but never worry if they don't - it maybe your taste is not floor taste in which case you wont get many spots ; you can alternatively buy for the floor, but if you don't love those tunes would you really want to play them ?)
Further
Grow a thick skin
I don't think being young is a disadvantage, it seems to be a useful coat hanger for promoters to hang onto - so if anything certainly makes getting an early spot a bit easier :-)
I'd like to see "newcomers" rather than youngsters given chances based on merit, breeds life into venues.