My backpack . just around 45 L , with a metal back support. inside this, I have a small sling bag , for my camera , notebook, and other stuff i carry out everyday.
As much as possible, both my hands are free of anything when i travel =) i hate carrying more than one bag on long distances.

Sleeved Shirts for cold destinations.
Plain colors are usually better on picture when traveling, the printed ones are just to obvious when you have used repeatedly. hihi =)
Also , I only bring cheap ones by the way (some, second hands), because there are times that i leave behind used clothes to give space for some stuff i bought along the way.
Always check on the current season of your destination, to know what type of clothes to bring. The time I went to Nepal, it was Spring of 2014, sleeved clothes were a big help. and Since it was cool, I never sweat a lot, so its ok to use clothes several times. No time for arte arte.

convertible pants to shorts. very ideal to bring, because personally, i only carry clothes good for 10-12 days , for a month journey. Usually, i just wash the light ones along the way, or just donate or leave them behind, to free up some space for souvenir shirts =)

Rolled underwear, placed inside a zipped fabric pouch, which also serves as my pillow. I don’t carry a neck pillow anymore since it uses up a lot of my bag.

quick dry gym towel 12″ x 24″ , and a small quick dry face towel. But i rarely use the gym towel, the small one is already enough for me

My passport, a small pouch for documents , and a tiny pen. Always carry a pen when traveling. More often, you have to fill up some forms for international airports.
Also, I carry with me a small notebook for expense tracking, and also just for taking notes of foreign sounding name of things I encounter.  Another thing, it is recommended to keep a few photocopies of your passport. Leave one on your big bag, one on your handcarry sling , and also if you have companions, give one copy to them, just for safety.

padlocks always come handy for backpackers. usually dorms have lockers but you have to rent a lockset if you do not have one.    The yellow triangles  are folded plastic bag , just in case i need some.

Mini Sewing Kit. Though i never used this so far. But the pins and mini scissor has been a help.

My Toiletry pouch. just around 7″x7″.
I usually carry toiletries in sachets (shampoos, deo) so it lessens my load as i consume it. A small bottle of Sunblock spf 50. a sachet of insect repellant. etc
Wet tissues are always refreshing, especially when visiting hot humid areas.

Anti microbial socks ( odorless) which can be used more than once.

mini tripod. monopod. The big tripods are not allowed for airline hand. When I backpack, I never purchase check in luggage, to save on ticket cost. 1 backpack is just enough with a month journey for me.  My Monopod got stolen by the way, when I was in Agra. =(

medicine pouch. tummy aches, irritable bowel , Vitamins, and nasal allergy spray.

invest in a good compact universal adaptor

As a solo backpacker, I really make an effort to do research before hand. I also study the locations of the sites I want to visit, and If it is walkable from a certain train station or a famous landmark accessible by cheap public transpo. Taxi is always my last option. =) As seen in this photo , I print out walking maps from maps.google.com , which is really helpful, and also easier for locals you ask along the way to assist with directions. Lucky if you get to have a real city map for free. But usually, google maps are already OK.   Google Maps application for android would be more ideal , if you have data plan with you when in travel.
Also as shown, I print out online tickets , and at the back of it, I print the hostel booking i have in that area of destination, to save up paper.