Check out www.onebag.com .  This web­site has a good pack­ing list, as does Rick Steves’ web­site, www.RickSteves.com .  For more than a month, you may not be able to get every­thing in one bag, but it is a help­ful place to start!  And you will not lose your bag.

Things that are either dif­fi­cult or impos­si­ble to find here in Italy, that you might miss from home:

• Med­i­cines and per­scrip­tions (Ritalin is not sold in Italy, for example)
• Zip Lock bags (yes really!)
• Sun screen in Win­ter is harder to find
• Index cards
• Tooth whitener

Bring copies of your pre­scrip­tions along with you–if you need a refill you can take them to a far­ma­cia and they will fill your pre­scrip­tions either imme­di­ately or within a cou­ple of days–often more inex­pen­sively than state­side prices.

Also bring any med­ical records along with you.  Ital­ians are expected to carry their med­ical records from doc­tor to doc­tor.  If you have a copy of your last den­tal x-ray, bring it along just in case– or ask your den­tist to make you a copy (usu­ally for aroung $5).  It is a good insur­ance to have.

And speak­ing of, espe­cially if you are going for a longer stay (over three weeks) con­sider buy­ing travel med­ical insur­ance.  There are sev­eral to choose from.  I use Amer­i­can Express Med­ical Travel Insur­ance (an Amex card is not required to buy the insurance).  Some fea­tures are… it  pro­vides in-country liai­son per­son­nel to help you as well as med­ical evac­u­a­tion plans, and pays in-country expenses for you while you wait for your own insurance’s reimbursement.