Venom's damage is greatly effected by Constitution, Continuity and Focus. At max level for these mods this adds 18 extra damage per second and 6 extra sets of damage. This takes Venom's total damage from 900 to 1638, an increase of more than 80%.
Venom is excellent for bosses with shields to prevent them from re-generating, specially against Ambulas since abilities target the torso, and MOAs take 3.0x damage on that body part.
Sentinels can also pop venom spores. This makes Dethcube the best sentinel to increase your chance at popping a spore currently to date.
Venom spores that are popped on a target's weak spot will take the respective damage multiplier. For example, if you pop a spore on an Ancient's head, it will deal 50 Poison Damage (25 x 2 damage multiplier). However, Venom's DoT ticks are unaffected by weak spots. Additionally, the AoE damage from popping spores is also unaffected by weak spots. Nearby enemies will still only take 25 Poison Damage from popped spores on weak spots.
Molt is very useful against regular Infested if placed during a jump - they'll keep attacking it without dealing any damage.
When using Miasma, be careful to not get knocked down during the cast animation, as once up again, Saryn will automatically repeat the cast animation, during this repeat animation she will take damage as normal, leaving you extremely vulnerable.