it has been 2 years since my trip to rome, florence, and naples [my absolute favorite]..and looking back now , the 2 things i did i STRONGLY advise..one, mentioned a lot: KEEP A JOURNAL! ..just a small spiral note pad, of daily events..the trip is So overwhelming, you will be glad that, at the end of the day, you made notes.
2- BUY A PAIR OF LEATHER SANDElS FROM THE STREET VENDOR!!.
these are suprisingly quality made.[italian leather? hello??] AND, i found they were the BEST foot wear for all those cobble streets and the never ending stairs.
the BONUS:, you will have a keepsake that keeps on giving..[my sandels are finally wearing out..after 2 years, for 12 Euro!!], but the memory is priceless. same for the journal: doing these 2 things will be like taking another trip to where you have been, free, no baggage check, just your memories.