Reposting from earlier:
grind the united nations mission on hard until you're kitted in full purples, it's like minimum 8 per run and it's stupid easy even with poverty gear. Then move on to the tunnel mission on challenging, you'll be grinding this for a while. Somewhere around like 100-120k sheet dps you'll want to move on to farming russian consulate. It's not nearly as hard as people make it out to be, and unless it's the daily only relatively similarly geared people queue for it. Even without the sploit farm hornet is worth farming, as he drops ilvl 31 high ends, including weapons, which unless you wanna grind DZ to 50 and farm DZ tech forever (fuck that), is the only source of high end weapons besides the vector.
Aside from that route do the two hardmode dailies for 30 phoenix credits total. You're first PC purchase should be the vektor blueprint, craft as many of those as you can. Out of like 10 vektors or so you're bound to find one that has at least like 2/3 good talents (you want some combination of armor shred/crit chance/crit damage/accuracy).
Once you have a decint-ish vektor and full purple gear you can likely just grind challenge mode missions as much as you want.