Do you only approach girls who give you IOIs?

[I_Dare]

If so, do you consider the popular Leil Lowndes book "Undercover sex signals" any good? If you have other sources please share.

I'd like to perfect noticing more subtle IOIs but in the same time I feel like getting good at this will limit me because sometimes women are very subtle.

My current mentality is that one should approach and see if a woman is receptive not wait for IOIs.

Someone said if a girl doesn't send you IOIs your chances are low, but I think sometimes women are just caught up in their head like most men... and there are tons of other reasons.