In an earlier post, I talked about planning a trip efficiently. Here are some websites that I rely on and have found useful:

My first stop ALWAYS is:
http://www.lonelyplanet.com

My next stop is the official tourism website of the country I want to visit:
http://www.germany-tourism.de
http://www.austria.info
http://www.spain.info
http://www.visitgreece.gr
http://www.visitsingapore.com/en.html

And then some others that I have found very useful on my trips:
http://www.roughguides.com
http://www.frommers.com
http://www.tripadvisor.com
http://www.dubaicityinfo.com/
http://www.greektravel.com/
http://www.explorecrete.com/
http://www.inyourpocket.com/
http://www.thailandforvisitors
http://www.touregypt.net

If I have a doubt I ask them on:
https://www.lonelyplanet.com/thorntree/forums
https://www.tripadvisor.in/ForumHome
The questions I want to ask will mostly be asked already, so I run a search and try to find the answers before posting a query.

There are many more websites that I visit (for travel tickets, booking accommodations, car rentals, etc.). But listing them all here might only cause sore eyes! So if you want to know more or need help, drop me a line and I will try my best to help. (No, I am not a travel agent or associated with any travel company. I am just your regular traveller).