Interviewing for startups : are formal cover letters + suits necessary, neutral, or harmful?

Work for a startup. Second startup actually, both successful. Wore a suit to both interviews. Results paint a pretty clear picture.

Even companies looking to maintain a casual, fun work culture should appreciate their candidates attempting to present themselves in a professional way. If an interviewer casts someone in a negative light because they wore a suit... I'll go out on a limb and risk getting flamed by saying that this person probably shouldn't be responsible for hiring in the first place.

The only universal rule is that there is no universal rule...

Companies, at any stage, are made up of a (semi)random collection of individuals. You can hardly predict their expectations, likes, dislikes, and expectations accurately.

Dress-code wise, I would say dress in whatever YOU feel most comfortable in. When in doubt err on the side of over-dressing, but for almost any "hacker" type role you would never go beyond a sport-coat (possibly with nice jeans and a dress shirt). As someone who has interviewed many people I would say that one thing that seems to negatively affect the dynamics of the interview is when you can tell the person is just not comfortable (and therefore not themself).

Along the lines of not being able to predict how people view your CV, I personally would rather see blank space on a resume instead of blather about what you did in high school or college, which is almost never relevant to what I am interested in. I also personally don't like people who send the followup emails of "It was such a great interview I can totally see myself making a huge contriblahblahblah". Save it, I get enough air-filled emails already, I don't need yours.

Despite what many people might say, there are a LOT of jobs out there. Wear what you want, and handle the process (cover letter, resume, follow-up) however you feel is most appropriate, and iterate rapidly over the feedback (or lack thereof) to adjust your approach.

Personally, I like a brief 2-3 paragraph high-level cover letter that is targeted to the specific job (matches your skills to my requirements) and a resume that is readable and underscores key accomplishments. Dress decent, no matter what position you're interviewing for (if you're at a startup you might have to present to a board or potential customer one day. Having a "nice" set of clothes is a good sign of preparedness, IMO).

The job I would like to have required me sitting around in my underwear and possibly a shirt. Joking aside, I don't agree with the dress like the job you want at all. It's important to convy professionalism. When you go to a wedding do you wear shorts and a tshirt because its comfortable? No, you want to look the part. A job is no different. I think its better to be over dressed then under dressed.

I work for a super casual company now. I wear a t-shirt and jeans to work every day. They actually asked me on my interview why I was wearing a suit. As soon as I spoke, they could tell I wasnt a stuck up stiff "suit". I showed some personality, smiled and laughed a bit. On the other hand I have seen people come through here in hoodies who get the job. But I would personally never wear anything less than a suit to an interview.

In the last job I applied for they dismissed a candidate because he showed up in tshirt and jeans.

In a previous job I applied for (electricians helper) they wouldn't hire you if you applied in a suit.

I believe in both jobs business casual was fine. It really depends on the interviewers though.

If I were interviewing you and you weren't wearing business casual I might ask why, but that's me. The reason I would ask why is it will give me insight to your personality, and circumstances. You might be having a tough break, you might enjoy wearing suits, or you might think appearances don't matter.

Your cover letter is your introductory email. (You're not attaching a PDF or anything, are you?) It should be conversational, well-edited, and concise, but should give the reader some reason to continue on to the resume.

As for when to start culling old info from your resume: I think you have the right idea in thinking that you should stick to those points that are directly relevant to the position. Padding your experiences and skills with high school activities may help when you're fresh out of school and have little or no professional background to reference, but if you've had even one full-time job in the industry, drop the kid stuff.

I haven't been on the interviewee side in a while, but from the interviewer POV, I personally like to see that applicants have made an effort to anticipate the office culture and dress appropriately. Seeing someone in a suit + tie when interviewing in a room full of people wearing T-shirts suggests to me that perhaps they aren't great at prediction based on incomplete information, and instead chose to "play it safe." That can be a desirable attribute in some positions, but it doesn't speak well of their ability to empathize.

If you want to find out whether you're going to get dinged for not going formal with your interview attire, do some research. Check the 'About Us' or 'Staff' page on the company website, or check out staff members' blogs and Flickr photos. Maybe on of the senior staff have presented at a conference recently, or podcasts from their office?