Luggage and bags:
On both trips, I brought one suitcase and my backpack. During my second trip, I also bought a kid's backpack in a bookstore in Salamanca to carry extra stuff that I was bringing back. Since it was lime green, it was easy to spot when I retrieved my luggage at the airport!
Clothing/Shoes/Weather Gear: Comfortable summer clothes for the day. It can get hot in the summer. It cools down at night, so it might be good to bring a sweater too. An umbrella is a good idea too (although it rarely rains in summer). I would bring trendy, stylish clothes for the nights, since that's what the locals are usually wearing.
On my second trip, I knew I would be doing a lot of shopping, so I didn't bring too many of my own clothes from home. I just bought clothes in the many stores and boutiques in town.
Comfortable walking shoes or sandals are a good idea, because of the cobblestone streets in town. But I never had any problems walking in heels around town.
Toiletries and Medical Supplies: Toiletries:
Shampoo, conditioner, soap, deodorant, and any other things you use regularly at home. I usually bring it in small bottles and containers that I can throw out as I use up the contents which helps to lighten my luggage load. But most necessities are available in town, though you might not find the brand you want.
Sunscreen (especially if you burn easily or are planning on spending a lot of time outside), bandaids (your blistered feet will thank you), your own prescription medicines.
Also, I had to bring a dose of twinrix (Hepatitis A and B) vaccine during my second trip (I had to take the second dose during my time in Spain, I went to a local clinic to have it done). If you have to bring any syringes, needles, or medicines, bring them in your carry-on, along with a note from a doctor showing proof that you're bringing them for medical reasons. Ask your doctor about what temperatures they must be kept at. When I brought the twinrix, I had to keep it in a fridge whenever I could.
Photo Equipment: Bring your own camera and film. But if you run out of film, there are many photo supplies stores around town where you can buy film, disposeable cameras, and get pictures developped.
Camping/Beach/Outdoor Gear: If you want to go swimming at the pool, bring your swimsuit and towel. But if you forget, there are stores where you can buy swimsuits and cheap towels.
Miscellaneous: If you wear glasses or contacts, bring a spare pair, in case you lose or break your normal pair. It didn't happen to me, but it's always a good idea to be ready for it.
If you're not fluent in Spanish or if you're going there for the language program at the U of Salamanca, I highly recommend that you bring a Spanish-English (or whatever is your first language) dictionary. It will come in very handy. Also, if you have a grammar book or anything like that, that can come in useful too.
Also, if you want to wear heels or other uncomfortable shoes, it's a good idea to bring tape. Just tape your feet where the shoes rub your feet the most, and you'll get fewer blisters.
I also brought a travel-size blowdryer with a European plug (I had bought it in Sweden). If you want to bring a blowdryer or other electrical device but it doesn't have a European plug, you'll need to bring an adapter too, and a converter if the voltage is different.
Luggage and bags:
Nothing special to take, just yourself and enjoy it.
Salamaca is one of the great places specially for solo travellers
Clothing/Shoes/Weather Gear: Maybe a book to read while enjoying a sunny afternoon in a terrace drinking a glass of wine?
just a suggestion lol