Grind out kills for guns, look up the ghosts, grind out activities. Guns kills are a matter of time. No one finds all the ghosts by themselves. Given where some of them are hidden and with 0 allusion to their locations you could spend hours in each area alone and not find them all, esp since there is nothing to tell you how many there even are in each area. PvP wins are the only thing I could see being skill influenced. For people who play with groups and friends and people who are just good, they will be able to get those wins much quicker. Everyone else it is still just a matter of playing it enough before you eventually get it.