Below are just some personal notes on the topic: Software Testing Tools evaluation. Information is not complete, verified and systematised. Some references will be provided in future.

A quick learning curve
Access to the source code
Allows for test case development
Allows you to start and  stop any time.
Allows you to write your test cases using high-level languages
Build in bug report systems
Capture test case results
Cross-browser Playback
Cross-platform support
Cost if not open-source (Price)
Custom Objects recognition
Define execution time at a future time
Debugging Support
Documentation (availability, amount, etc.)
E-mail (Allows you to send e-mail messages )
GUI Object Recognition
Generate useful metrics and statistic
Have a capability for monitoring execution cases and test data.
Internationalization Support
Licensing 
Launch applications or processes in parallel or in series.(Launching processes on multiple machines)
Multiple Test Suite Execution
Multiple platform support
Multiple process management
No external dependencies
Open-source
Performance
Platform Support
Provide a way to manage test cases for execution.
Programming language (Support high-level languages)
Recording Browser Objects (IE, Firefox)
Recording Java Objects
Recovery System
Reports
Scalable
Scripting Language
Support (forums, mailing lists, etc.)
Support of distributed environment
Support multiple platforms and OSs.
Technical Support
Test case Management
Test manager feature
Test results reporting functions
Test scripts management
Training
Web-based interface
Supporting Java
Visual Test case Recording
Common IDE integration

First of all you need to define the areas of your system that you would like to create test automation. You can create questionnaire and give it to different people who is involved in different aspects of development and testing. The possible areas of automation can be defined as: automation of data creations for testing, regression testing automation, load and stress testing automation, automation of multithread testing, back end testing, GUI testing, link testing, security testing, etc. Some tools can be used for different types of automation. In the same time you need to define testing environment: what operation systems, databases, types of browsers will be involved it testing and what programming languages are used in development ( you may be will have to ask developers to help developing automation scripts for testing) or knowledge of what programming languages you have in your testing team. Now you can start preliminary tools evaluation. Try to Google your requirements and do not forget to evaluate tools from testing tools page on this site.

Guidance for creating text in a template.

On this site you can find information about software testing
and  automated software testing tools, recommendations for
software testing training course, list of books about software
testing with recommendations and books suggested for software
testing certification, online software testing quiz, interview
questions for software testers, software testing dictionary,
samples of software testing documentation including test case
template, jokes about software testing and testers, software 
testing techniques and more ...