First of all, those starting items are really good for Chen to support your allies. Once you have a creep that could have a potential of ganking (Centaur, Dark Troll Warlord, or Ursa Warrior) try to help a lane that you think can get the easiest access of First Blood. Smoke of Deceit will help a lot. Try to get your Mekansm as soon as possible, so your team could start a war at anytime.

Best of Luck,

Captain Clumsi