Please tell me how

Once you get to lvl 1 you do pvp till lvl 4. You pick up those bounties you have to do on earth. Do 2 missions and patrol and you will have the 3 bounties. Hand them in and you can get 3 other vanguard bounties and 3 pvp bounties. You then go back to pvp and don't stop until you get all your pvp bounties done. At this time you should be almost lvl 10 or 11. You hand in your pvp bounties and you reach lvl 12. Once you hit lvl 12 you unlock the other half of the daily bounties so pick up the other pvp bounties and the other vanguard bounties. Then go back to pvp. (Oh yeah pvp is everything gives you 60 xp and you get 1800 bonus xp at the end) once you finished your pvp bounties go hand them in and you should be around lvl 15, 16, maybe even 17 depending on how long it took you. Then you go and do your vangaurd bounties and some missions and you'll be lvl 20 before you even hit Venus. This method only takes me 8-10 hours to get a guy to 20

Holy crap im doing that right now! Thanks!

8-10 hrs is way too long