The weather in your travel destination may vary. We would suggest that you pack layers of clothing. Apps such as Packr and PackPoint will give you great packing tips based on forecasted weather. A light waterproof jacket may also be useful and a sun hat during the summer months. Bear in mind that some excursions will take in visits to cathedrals or other religious locations where there may be a restriction on shorts / mini-skirts and bare shoulders. A comfortable pair of flat shoes /trainers for walking is essential as you may be visiting cities and sites with cobbled streets and uneven terrain. Useful items that you may wish to pack can include:
Phone charger
Medication
Adaptor plug
Travel iron
Carry bag
Travel pillow
A photocopy of your hotel contact list & photocopy of documents
A photograph of your luggage contents for reference