I was recently updating some of my Stack Exchange profiles and I remembered how much I hate writing about myself. It isn't just Stack Exchange profiles either. It's resume cover letters. It's college application personal statements. It's blog and book jacket blurbs. It isn't the easiest thing in the world to come up with good things to say about myself and then when I do I have to be careful not to come off as arrogant. Now, I'm not asking for help overcoming my personal neurosis, but rather is there is an approach that will help me be objective when writing about myself and allow me to evaluate what to leave in and what to leave out?
First, let me just say that arrogance is underrated. And you're talking about pretended objectivity on a subjective topic. It very much is subjective. It feels stiff and wrong to be "objective" because it's very much not. Pretending as though you are just feels off. Truly, no matter how much you pretend, you are not actually objective when it comes to yourself. There's always some kind of bias. Even if that bias is over-correction. So be aware of that and play with it.
Most people reading these things aren't doing it for fun--they're doing it to get info, because they are curious or need it to make a decision.
Each one of these is a genre to itself (which makes this question too huge to completely cover)--for a blog or back cover you can be funny and irreverent.
So the very first thing is What do they (the reader) want and what do you (the writer)want? Basically, you have to ask yourself, as you do in most writing, what the reader is looking for in this piece of writing and what you want to convey to them.
If it's a college essay, the reader wants to know about your accomplishments and you want them to be impressed enough to get you into their program/give you a scholarship/whatever it is. If ever there was a place to brag, it's here. If it's a book jacket, you might want the reader to feel certain feelings about the author so they will pick up the book.
It's not bragging if it fulfills a necessary function.
2-to-1 rule. But merely fulfilling expectation isn't memorable, and the objective to be memorable is often part of what you want to convey. So if there's room to have fun, have fun. Somewhere in there, write about two boring things (valedictorian, winner of the newberry medal) to one irrelevant or interesting thing (once jumped out of a plane naked, a story for which you will have to interview me to find out about, OR is an expert cat cuddler OR the tip of my nose always sunburns, no matter how much sunscreen I apply). Make yourself a list called "Weird/Awesome Facts about Me."
How did you get there? There's being the Valedictorian and there's how you became the Valedictorian. Those are two different things and you can show humility if that's your goal. Accomplishments are one thing saying something like "I achieved the honor of Valedictorian. I could put that forth as evidence of my brilliance, but it's merely evidence that flashcards work. For the duration of my high-school career I was never without--my best friend enjoyed the experience of yelling vocab words at me as I played Diablo III."
When you talk about how you "got" to an accomplishment, you can give the reader a better picture of you as a person, not just a list of facts. In the above, you aren't just a Valedictorian, or a list of accomplishments, now, you're an actual person. You're the guy who carried flashcards everywhere--who got his friends to drill him even as they were having fun--and you are definitely a hard worker. Oh, and HUMBLE too. LOL.
Show, don't tell. You can't get around the fact that you are bragging. Come to peace with that. But your job isn't to TELL them you are awesome. It's to show them. Go and read Jay's entry--basically, he's advocating showing the results of awesome rather than just stating awesomeness. You show that you're good at being in charge by saying you managed a team and what that team did, and perhaps how they improved under you. But you don't just say that you're an awesome manager.
Repetition is boring. Each and every item you mention should have an objective, a la "what you want to show the audience." If several items fulfill the SAME objective, that's repetitive, and looks like you're bragging. An entire essay that can just be reduced down to "I am very smart," is a problem on so many levels. Say more than one thing in your subtext!
So, in answer to your question: is there is an approach that will help me be objective when writing about myself and allow me to evaluate what to leave in and what to leave out? I say, you are never going to be objective, you can only SEEM that way. But as for an evaluation of what to leave in and what to take out, just ask: Is it interesting? Does it give the reader what they want? Does it convey what I want? Is the subtext of what I am saying repetitive?
I guess this is more of a psychology question; but -- as a fiction writer -- you can try writing about a fictional character. Change your name!
It is a trick to distance yourself from the work; write about George or Mike instead of yourself, but using your own biography and accomplishments. In 1989, George did this; in 1991 George did that. Once you have described George well enough for readers to understand him; revise the profile, without adding or deleting anything, but to make it a first-person narrative.
As in fiction, to be realistic, George likely wouldn't reveal his worst flaws and sins up front. Everybody puts on their best face to meet strangers, and expects the same; so if you are completely honest and tell people you are "indecisive at times", they gather you are minimizing, and take it as a warning you are indecisive all the time, to the point you feel you need to warn people you are irritating.
I do a less extreme variation of this writing about my own past; I just imagine my past self as somebody I know, and have much in common with, but not the current me. Which I feel is true; I'm certainly a different person than I was as a teen, or soldier, or college student, etc.
I personally struggle a lot with writing about myself and worrying about coming off as arrogant as well. But, I do at least feel like I know myself reasonably well, due in part to a couple of things that I do: -Write in a journal. There really isn't much of a formula to writing a journal, but I feel like if you write enough, you'll start to see patterns emerge. For example: looking back on my entries, I found a lot of entries where I said I was going to do something, but then I didn't end up doing it, which was a pretty surefire sign to me that I'm indecisive as all hell and not very proactive. (It's amazing how we need to do such tedious things to find the most obvious thing about ourselves) -Do the self-authoring program. Now, this one does cost money, but I know personally that it helps a lot with self-confidence and finding purpose in life, which can tell you a lot about yourself.
Granted, these aren't exactly answering the very specific question you're asking, but I feel like if you know yourself well enough (Know what's most important to you, know which part of you is the most immutable, etc.), it can very well help you decide what to write and what not to write in any given situation.
Again, sorry for the somewhat indirect and maybe not immediately actionable answer, but I hope it offers something of value to you.
This is a big subject that probably can't be answered in a brief post, but some thoughts that come to mind:
Give objective facts, not subjective evaluations. For example, "I was valedictorian", not, "I was the smartest person in my class". Or, "I was responsible for managing the inventory for 20 stores", not "I was the only one who knew what was in the stores", etc. In general, avoid saying "I am/was the best ..." or "most important ..." or similar words. State the job responsibilities.
Don't be afraid to relate your accomplishments, but avoid overstating. "My re-organization plan saved the company $10 million", not "I saved the company."
Something I still struggle with: Should I mention honors or achievements that may be 100% factual, but just sound like bragging? Like I used to be a member of Mensa, the high IQ society. Should I say that, or tell what my score was on an IQ test? I generally don't, but I think that one is not clear-cut. In hazy cases like that, I think it might depend on how many other good things you can say about yourself. If you don't have easy-to-describe achievements -- whether projects completed on the job, sporting matches you've won, whatever is relevant -- I'd be more likely to include hazy things. If you've got plenty of clear-cut things, you don't need the debatable ones and can leave them out.