Ayy, I've got a -1/-1 deck, too! And I'd recommend going into green as well, they've got a lot of *really* good -1/-1 cards.
For more token generation, '
Hapatra, Vizier of Poisons' does a whole lot of work.
For raw output of -1/-1 counters, pair 'Examplar of Strength', which when it enters the battlefield, it puts three -1 counters on a creature you control, with '
Soulstinger', which when it enters the battlefield puts 2 -1 counters on itself, and when it dies, put as much -1 counters on it onto target creature. If you play your cards right, playing
Soulstinger first, and then Examplar- putting exemplar's counters onto
Soulstinger, you put out 10 -1/-1 counters with two cards. And if you've got your token generators like Hapatra, and
Nest of Scarabs up, it gets *ridiculous* quick.