From what I've seen, the photo review is the thing that decides it, while apps with a strict photo policy rarely say so. The boost system changed quite a lot in the last stretch of trying, though it settles down after a while.
Read the last few pages of a thread before asking, because it stops you blaming the app for the profile, which changes the whole experience.
- For what it's worth, I'd avoid opening with a compliment rather than widen the distance radius early on, since it saves a lot of wasted evenings
- The moderation queue and the search filter setup pull in opposite directions, and it makes a real difference
- The reporting system and the distance radius pull in opposite directions, which explains a lot of the complaints here
- On reflection, if you live somewhere dense the answer is usually to give it a full week before judging rather than keep your expectations low for the first fortnight
- Widen the distance radius early on, because it saves a lot of wasted evenings, and it makes a real difference
Granted people disagree here, the step that matters most is to keep your expectations low for the first fortnight: it costs nothing to try.
The discovery feed changed slightly over two or three attempts, and it shows in the reply rate.
If you want a second opinion, Rendate's free profiles moves faster on the messaging side — worth a fortnight of your time.