Krabi – and Thailand in general – is a very safe place for solo female travellers, with the exception of late night bars, which is probably the case in most places around the world. Precaution is advised in such venues – we would recommend for example only drinking bottled drinks such as beer, which are opened in front of you. Drinks in glasses (or worse, buckets!) can occasionally be spiked. (Note: if you will be travelling on to Koh Phangan for the Full Moon Party or anywhere similar, please, please heed this advice even more carefully, as drink spiking is sadly fairly commonplace during these parties.)
Another drink to avoid, if you have no one to carry you back to your room, is “lao khao”. Often sold as “Thai Tequila”, it is a particularly potent and nasty type of rice alcohol that sells in the supermarket for around 30 baht a bottle – yes, that’s right per bottle – the same price as its close relative, gasoline.
Similarly, due to the actions of tourists – both men and women – who have been here before you, many of the locals who hang around in bars at night tend to assume westerners are promiscuous. For women, simply dressing conservatively can help to avoid unwanted attention in these cases. Of course, if you do want the attention, then take the usual precautions and never get so drunk you cannot take care of yourself – this applies to the solo male travellers as well! Though Krabi is no Pattaya or Patpong, and there are very few “red light” areas, any single males out at night in Krabi will get far more attention than the females. Caveat emptor.
Other than that, nothing other than the usual common sense safety measures will be necessary (e.g. not leaving money / phone lying around, don’t drink and drive etc.). Street crime is very rare here. And, to talk about the positive side of solo travel, Krabi is a very friendly place: if you would like company or just some small talk, most people (locals and expats) are happy to have a chat.
In terms of where to stay, central areas in Ao Nang are a good bet, or if you climb or plan to chill out on the beach, try Ton Sai Beach or Railay which are both small and fairly sociable. Note that the vast majority of hotels in Krabi charge per room, not per person, so single traveller discounts are rarely offered, though in some backpacker places they may respond to face-to-face bargaining. If you don’t mind sharing, there are several hostels offering dorm accommodation, both in Krabi Town and in Ao Nang.
The most economical way to explore the area would be to book one of the many organised tours available – this is especially true for the islands when private boat charter may be over budget for one person (or get a group together from your hostel and go). For inland exploration, there are more tours, or you can rent a car or motorbike. It’s very easy to get around and places are clearly signposted; free maps are also readily available from most hotels and booking agencies.