The Best thing for bein a natural is goin out there and being spontanous!
theres not to much you can read about bein a natural you just develop it from being out in the field and not using canned routine material...

walk upto a girl and say hey, maybe comment on something shes wearing, but dont jus tell her you like something shes wearing also tell why you like it, this shows to her you've actually put some thought into it...

then basically take it from there see were the convosation ends up =]