An important post from Backpacker:
DO be friendly, but not aggressive. If a woman doesn’t seem interested in having a conversation with you, back off.
DON’T ask solo women where they’re headed or where they’re camping.
DON’T use sexual innuendo.
DO give solo women space. Keep distance between your tents if you end up camping in the same area.
DO be extremely cautious about flirting. Don’t make her feel like she has to change her pace or otherwise compromise her hike to escape from you.