Turkey - Appropriate Clothing for a Female

I traveled all over Turkey as a solo female, and dressed just like I did on any other trip - usually I wore business casual long pants (no jeans) and a knit or cotton top with short or long sleeves. You might want to bring a lightweight sweater or jacket if you're there in October.

The only difference with Turkey is that there are dress codes in the mosques. I brought a long wide scarf along so that I could wrap it around my head and shoulders in keeping with the dress code. Some mosques have scarves available for women to wear, but I preferred my own. Just make sure you don't wear shorts or very short skirts or have uncovered shoulders in the mosques.

Some cities are more conservative than others. I tend to follow a 'covered shoulders, knees and cleavage' for most day wear, and on mosque days, 3/4 or long sleeves and a scarf for the head, neck and any other bare skin above a collar. In very strict countries ( Middle East), I wear a skirt or tunic that falls below my torso (so add 'covered crotch') with long loose trousers.
Have a pair of shoes that are easily removed and put on for mosque visits.
If you fail the modesty check at the entrance, they have paper sheets or scarves to rent to cover up the offending area.

Are you going on the Best of Istanbul tour or the Best of Turkey tour? If the latter, then you'll need a variety of things, including the conservative wear and a head scarf, as mentioned above, especially for entry to mosques.

For some of the sightseeing days at places like Aspendos, Pammukale and Ephesus, you'll want sturdy shoes to scramble over uneven stones, stairs and paths. In October, it's likely you'll still want a sunhat/sunscreen. If you're taking the optional boat ride in Antalya, you may wish to bring a swimsuit and coverup as we were allowed to swim and dive off the side of the boat.

I took both tours last May and you can find more details about clothing in my Trip Report:
https://community.ricksteves.com/travel-forum/trip-reports/3-weeks-to-fall-in-love-with-turkey

And I've answered a lot of the questions that I've been asked about the tours in this post:
https://community.ricksteves.com/travel-forum/tours/so-you-re-going-on-the-best-of-turkey-or-best-of-istanbul-tour

Hi from Wisconsin,
Modestly.
wayne iNWI