I'll try to include just as much advice in this review as I do insights. My first tip is that if you haven't already applied and you were planning on doing so online, reach out to someone in the role on LinkedIn who you share a mutual connection or alma mater and ask them to refer you. It's good for them and your resume will get looked at much faster.
After you've applied, your first step will be a scheduled call with a recruiter as an initial screen. These will be easier questions (tell me about yourself, past experiences, a time you succeeded that you're proud of,) typical interview questions. They have your resume, so expand on what they don't see and shine.
Next step you'll likely talk with another recruiter in the field they think you best fit. This interview will be harder questions ALL behavioral based. Research behavioral based questions and know the STAR method. At the end he will likely tell you if you're moving on to the next step.
The next interview will be with two managers who currently work supervising people in your role. These questions will be more tough than before and remember that at each step they take notes so don't repeat examples you've previously used. Be specific in your examples. My best advise here is for every experience on your resume think of four or more specific examples in the STAR method to have ready. They ask you questions back to back and you don't want to stumble, ramble, or blank. They will also give you time at the end to ask questions: make these questions insightful and have them prepared.
After the third interview you should hear back within a day or two over email. Then the last step begins. They will coordinate travel if you're out of town (flight, hotel, rental car, etc) and fly you in for a panel interview. On the panel will be two or more managers (likely the ones from your last interview,) a VP in your area, and your recruiter. You will give a 30 minute presentation on yourself, and the panel will ask questions throughout and at the end. Be prepared to answer tough questions, by being prepared with examples of times you've overcome difficult coworkers or situations. Be yourself; they already know you're qualified if you made it this far. You'll want to show them who you are at this round. Be professional and confident most importantly.
Immediately following the panel they will give you instructions on how to craft a follow up email; follow the guidelines, be prompt, and show them you're literate. This is the last 'interview' step.
After the panel, which lasts two hours, they will make a decision and you should hear back within a few days. It took them two to get back to me which was nerve wracking, but you should feel either bad or good about it when you leave and have a sense.
Overall tips for the process: be patient, each step takes time so keep that in mind. Take notes. They give you feedback at every step, write it down and remember that for next time. As you think of questions, write them down for later. You'll be asked to interview them as well and come armed with insightful questions. Prepare prepare prepare. If you think you've prepared enough, prepare some more. You'll feel more confident and perform better at each stage.
Previous reviews have stated that the interview process is difficult, which it is. But it is only difficult because you have to go through four different (and stressful) rounds of interview, wait, hear back and repeat. Prepare for this now.
As someone who has been through many stressful situations, the stress that Gartner puts on its candidates by making them go through four separate interview steps is unnecessary. My biggest issue isn't that there are so many interviews (although it isn't the best attribute,) it is the length of time between steps and how long it takes to go from applying to being hired. If you can't commit about one and a half to two months to this process, it isn't for you. This was my only negative with the experience. Every step of the way the recruiter, the coordinator, and management will be rooting for you to succeed. Gartner is an incredible company and it is easy to see why they want to work hard to hire only the best.