When I first started traveling, I wish I had known about some of these but now I have started a collection for you, here :)

* = sites I've personally used and recommend. 

Meeting people

Volunteering/Accommodation

Book planes-trains/busses-carsharing

goeuro.com
rome2rio.com
Denmark:
rute1000.dk
Germany:

Other

Accommodation

My favorites

couchsurfing.com
skyscanner.com
google calendar
goeuro.com
---------------
google trips
​google keep


General Tips

There will be many more here, soon!

  • Bring an old cell phone. nice to use for wifi in emergencies. offline maps. notes. pictures. if you get robbed heaven forbid, you lose a crappy phone. 
  • meet some locals online before going. you will have someone to show you culture. best places. places to avoid etc. you have someone to introduce you to more people. 
  • loosely plan a few things like what you want to see but don't plan every detail or worry that you aren't following your plan. 
  • buy a waist hidden money belt. 
  • buy a portable device charger.
  • politely ask a million questions. you will learn more and quicker with less learning mistakes. People will either smile, be rude, make you feel welcome or unwelcome. but sometimes you meet a new friend or just a friendly person. Sometimes you meet someone who doesn't like you because you are from or they are just having a bad day. bless them and move on towards finding the right people. 
  • it's nice to take pictures of things that are cool but if you do this too much it prevents you from being in the moment and soaking up all that is around you. memories last as long as pictures but better. take pictures of general places so you can look and imagine yourself being there back in that moment or laugh at the things that happened right then. 
  • When things go wrong as they inevitably will, remind yourself that in a week or a month it won't matter at all and you'll be just fine. You are learning and improving yourself and travel skills. 
  • withdraw and pay in currency in the local currency and use a card that doesn't charge foreign transaction fees. local currency means there isn't a conversion fee to your home currency. 
  • keep a travel journal, its a pain in the ass but you will forget things and it makes your trip last longer than the time you are there. 
  • Try at least one local food from each place you go.
  • Purchase round-trip airfare or make sure that you will be allowed to enter wherever you intend to go, without proof of your departure back to your home country.
  • wear sweatpants at the airport so you don't need a belt ;)
  • For long or far trips, pack three times with days in between in order to re-examine what you actually really need to bring.
  • Set your phone or watch to the local time of the place you are going, a few days in advance to start adjusting to that time zone.
  • Bring 50 Euro equivalent worth of currency for wherever you are going, in case you can't use a credit card or find an atm. 
  • Bring a good padlock to use in hostels and lockers. 
  • Bring your favorite brand of cold meds or other similar items which may be hard to find in a foreign language. 
  • I personally recommend waterproof leather boots for most traveling. Make sure they are comfortable, durable and stylish with any clothing. 
  • When packing, keep in mind you will probably find clothing or other stuff that you might buy. 
  • Google search whether or not it is safer/smarter to take a cab or an uber etc in the place you are going. It is different everywhere and some places run scams.