I have interviewed candidates for ThoughtWorks. Over a period of time, I realised that there are a few general things ThoughtWorks seeks or desires from a prospective ThoughtWorker.
* Are you good at software development?
The first thing TW wants to know is that if you can code. And how good is your code?
The goodness of any code is measured by the cleanliness of the code; the design of your solution; the ability of the reviewer to read and understand your code (this is subjective); Your discipline in terms of following general conventions, guidelines and good practices of writing code.
* How good are you at what you do?
Your resume reflects your work history in brief. Everything you mention in your resume helps the interviewer understand bits and pieces about you and your work.
Most of the times interviewer wants to know, how well you know what you claim to know. Various inferences are made based on your knowledge of certain topics.
Retrospect on your past projects, what are some of the achievements you are proud of (and why), some of the harder problems you have solved (and how you have solved them), your opinions about technologies, frameworks, programming languages. And if you are passionate about your work, its a big plus.
* Your ability to fail, learn and adapt.
There will be questions that test your ability to grasp information, learn from it and apply it to a problem.
The questions are generally in a form of object modelling, pseudo-code for an algorithm, solving a real-world software problem or something from your work history.
Practice object modelling. Practice multiple solutions for system/architecture design (even for your daily work). Never fail to try.
* Are you fit for the organisation?
In all the interview rounds, you will be assessed on various aspects. Aspects that matter to the organisation.
Some very simple questions, the interviewer asks himself while evaluating a candidate is:
Will I be comfortable working with the candidate?
Will the candidate adapt to the work environment?
What would the candidate bring to the organisation which could be helpful for the business as well as the community?
Take clues/suggestions from the points mentioned above to better prepare for the interview.