But the one thing I need for medpacs, green goo, I never get from my bioanalysis or diplomacy missions I send my droid on. I'm currently on Balmorra and I rarely fight creatures or find plants to harvest, so it's proving pretty hard to advance my biochem.
Green Goo is extremely common off the potted plants (and occasional organic corpse) in Coruscant. At your level you can just double back, dodge the very low level bad guys, and scoop up as much as you need. This is, however, time consuming so you might want to snag a stack off the GTN. If listings are high enough to make your wallet tremble, consider using as few as possible to level past tier one - and then sell the rest to turn a nice little profit. Even with the time spent running around, it's much faster than waiting for the right kind of mission to show up, then sending out a companion and hoping they bring back the right samples.