I've found there's a strong correlation between pictures, especially sexy or cute ones, and creepy messages for sex-crazed jerks. I try to keep mine to a minimum and usually unidentifiable.
Also, uncheck casual sex. That affects whose profiles you show up on. If you're really only looking for long term, then maybe even check only that. But you might narrow the field too much.
Another good idea is to answer lots of polyamory related questions, with corresponding the corresponding answers marked "mandatory." That helps improve your %age match with like-minded people.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker