Breaking it Down
There are many things that should be looked at, described in no specific order.
Standardized test scores such as the GRE and TOEFL are the first things you should put together. There serve primarily as elimination criteria and not selection criteria, so while very high scores may not do much more than getting you in the door, mediocre scores will certainly work against you. The range of mediocre to high varies by program which we'll look at later.
University GPA or aggregate is the second thing you should consider. Whichever university you may be in, your absolute undergraduate GPA and more importantly rank in your department can be big positives in your application. If you did not do so well, then aim to get very high scores in the GRE and TOEFL, as this lessens the impact of low GPAs.
The letters of recommendation from your professors or your bosses can make or break things on their own. Suffice to say, these should be accurate representation of you and your relevant work. You will need at least two positive LoRs so make your decisions about whom to ask wisely. Most universities require that at least one of the LoRs is from an academic adviser or professor, so try to keep in touch with one or more of your undergraduate professors once you are working in the industry.
If you have engaged in research work in the past, it will be a huge plus to your application. Published papers are the primary evidence of having pursued a productive research project and these provide a significant boost to your application. If your project did not result in a publication, fret not. Try to get a LoR from your research adviser, clearly mentioning the work you did, and what the end result was. Also, try to have included mentions of the impact of your research in the LoRs.
In continuation, you may have worked on various academic or hobby projects that led to some usable product at the end of it. These, if relevant, should be included in your application as it indicates that you may have practical experience in the domain. Hobby projects in particular demonstrate that you are willing to go beyond the course requirements to pursue your interests. This is very important if you are applying outside of your undergraduate major or if you feel that your university did not offer as many opportunities as you would have liked in the domain of interest.
An alternative to the above is to describe relevant work experience, or parts of your work responsibilities that ascribe to you having the necessary qualities to do well in a graduate program. These included both technical and non-technical attributes. Obviously, work experience in the relevant domain will help your application the most.
Lastly, we come to the extras that while by themselves are not big aids to your application, they help embellish your application by painting a picture of a person who has interests outside of the classroom and lab. Here again, relevant technical experience such as blogging about your technical interests, publishing in magazines, running or participating in a local technical user group, competing provide small bonuses. Non-technical experiences such as organizational work, leadership roles in the university, volunteering in social organisations, and other things can also be of help.
Putting it together
- Research work and it's evidence come first. These should be described in detail in your application.
- Letters of Recommendation describing your research contributions and providing information about your class performance (ranks and not marks).
- Relevant work experience or relevant parts of your job come a close third.
- University GPA
- Academic or hobby projects should have samples or documentation to support what you say you have done are very important.
- Standardized test scores come nearly last. Yes, last. You only need to clear the minimums required by a program. Beyond that, it does little to strengthen your case.
- The embellishments while not taking much space should be included wherever possible in your application.
You should have a nice list of experiences jotted down. These will help you figure out universities to apply to as well as what to put in the different parts of your application. This will vary depending on your own experiences so far. There is no one size fits all approach.