Some more tips after a bit more expierence:
Omnivore
Dustpaint's mouth tip is true - one in the middle and 2 on the side (I prefer carnivore in the middle)
Once you get the omnivore mouth (which is actually a great attacking mouth) when you go suck someone up, you can spin them around and use them as a shield to an oncoming predator.

Carnivore
The omnivore mouth i find is the best carnivor mouth
It is easier to play late cell stage as a carnivore, but harder in early game.
You want a balance between attack and speed (see my other post for a good build)

Herbivore
Harder late cell stage, but easier early cell stage
You practically only want speed so just put jets on first, and then when you can afford it put on 5 flagella

General
When putting on body parts, shrink all your body parts to the smallest size and then place them, this way you can fit more parts closer together and get them exactly where you want them, then you can enlarge them again( use mouse scroll for this)
mating is a good way to get away from a predator
Spikes i find are the best weapon
jets are the most cost efficient speed booster, but flagella are the best (IMO)

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