the DM is classed as a "Spoolie" or Spool valve gun. If you like that sort of system, have a look at an Etha, they are very well made and you can pick one up on the forums for a very reasonable price. An excellent starter marker.
My advise is you have your mask, Next I'd suggest purchasing a Hopper and Air tank, this way you can borrow markers and use your own air/hopper. This also gives you a chance to try out various markers to find what you like best. (and save for it.
Also do you have playing kit (pants etc?) whilst not as important. as you can wear camouflage kit or anything really.
Also if you eventually join a team they'll have their own preferences to playing gear.
That said a pod pack can be useful too.
next tip, get out and play, walk ons, big games, open training sessions and the like always worth attending, as are pro clinics held by pro players will help you with your drills and skills.
Buying kit:- I would recommend things like mask be bought new or if bought 2nd hand, buy a new lens as 2nd hand ones can be scratched and maybe weakened. and the Air tank new as this will give you the expanded lifespan and not require testing and so on.
But the rest of it, pants, jerseys, markers, hoppers can all be bought 2nd hand, and some bargains to be had.
There are bits and pieces drill wise you can do at home, like practice a snap shot in front of a mirror, to finger "rocking" on both hands,
exercises to build up stamina.
and field postures so you can make yourself as small a target as possible but maximise the attack on your opponent.
hope this gives you something to go with.
If you can, pick up some copies of PGI, always full of tips and tricks from professionals and players all over the world