Spent most of last winter on free-tier sites, so here is what I actually saw.
What I wish someone had told me about free-tier sites: use separate photos from the ones on your other accounts.
If you are starting with free-tier sites, assume the first three conversations will go nowhere.
Worth doing early on free-tier sites: test it on a weekday evening, not a Sunday morning.
Everything about free-tier sites hinged on whether messaging was actually free or free-to-a-point in the end.
If I had to name one factor in free-tier sites it would be how many accounts looked dormant.
Others here will know more about best free sites for online dating if you live than I do.
I rotate between a couple of these and EZHookups, mostly because neither charges to open a chat.