Put any containers holding liquids in a sealable plastic bag. On your return home, refill the items you've used and the bag is ready for the next trip. Keep a bottle opener or corkscrew in your suitcase or toiletries bag. Pack a collapsible bag for new purchases, dirty clothes etc. Most airline carry-on restrictions do not apply to purses, coats, diaper bags or camera bags.
Restrictions usually do apply to briefcases.
The flight attendant has the final word on whether or not a particular bag goes on board or must be checked. On many flights between two international cities, baggage is limited by weight rather than number of bags. Excess weight charges can be levied if your bags weigh too much, so be sure to check with the airline about each leg of your flight. When checking your bag with an airline, remove shoulder straps and other loose items that could get caught in conveyer belts. Label your luggage inside and out with your name and a contact phone number.