here's what i did.
for a while i gave what now is my gf but wasn't back then kisses on the cheek all the time. start doing that for a while until she gets comfortable. then you start doing these half cheek kisses. (not to be confused with half ass kisses) i basically kissed her at the corner of her mouth so its kinda getting close to a real kiss, but not really. do that for a while and if she seems okay with that, then u can seal the deal.
its like a nicotine patch, if u can't do something right away, do it in steps. good luck