Combined Suggestions, Machu Picchu
Seasoned travelers will already have a good idea of the necessary items which need to be packed to help make any given trip a little more comfortable, to protect against the elements and pesky insects.
First and foremost, good non-slip shoes for climbing or hiking are a must, followed by bottled water, then a light-weight day pack to carry money, ID, a hat, sunglasses, camera + extra memory storage, medications if necessary, hankerchief/tissues/wet wipes, passport (for stamping) a map of MP, a light-weight poncho (weather changes rapidly), and maybe a light sweater/sweatshirt depending on the time of year. Carrying anymore than this will do more to hinder you than help you due to the amount of climbing involved.
No food is allowed in the park as are no breakable containers for liquids. A good advance application of lip balm, sunscreen and/or insect repellant prior to entering the park should do the trick.
Miscellaneous: If you're extremely fortunate, at the end of the day you might be returning to Sanctuary Lodge for the evening and can plan to see Machu Picchu all over again the next day!
Luggage and bags:
Small backpack for the stuff you need with you
Clothing/Shoes/Weather Gear: Sun hat, rain poncho
Toiletries and Medical Supplies: Sunscreen--heavy duty kind, and use more of it than you think you need. You burn quickly at that altitude
chapstick or similar lip balm--the dry air takes a toll
WATER - dehydration makes altitude sickness much worse
Miscellaneous: Picture ID of some kind - If you exit the site and want to go back in, you have to show it.
toilet paper - often there isn't any