Sometimes feedback can be on your little quirks. I was once told I look to one side of the classroom more than the other when I speak. I was totally unaware of that. I have since tried to share out my looks more equitably. However, I also remember in one of my first jobs in a fly-by-night academy the director said I spoke from too far back in my throat. He didn't tell me how to change that.
Anyway, I find if you want to do well in an observation the main thing is to be absolutely clear what the aim of each activity is. Once I was surprised to find myself tripping up a bit in that department: I normally pride myself on having clear lesson aims. I was teaching an upper-intermediate class using a First Certificate book and I had planned an in-class reading. Anyway, I had the students read aloud: one student would read one sentence, then the next student the next sentence, and so on. My idea was to correct their pronunciation as they read. This stage of the class was really about pronunciation, then I would “exploit the text” (that always sounds comical to me).
Anyway, my observer was doubtful that this was time well spent and thought that just doing a straight timed FC reading, focusing on answering comprehension questions, would have been more fruitful. I must admit that hadn't crossed my mind, primarily because reading is so easily given as homework; but that day the students needed to be “exposed” to this text in class so I could move on to highlighting language in it. So the observer opened my mind to the possibility of doing straight readings in class.
Once an observer thought I should pick up the pace of my lessons by gearing them to the fast students: that way things would be faster, livelier, bouncier. The slower students would just have to do their best to keep up. Actually I have taken this to heart, though sometimes slower students feel left behind and then slow things down by asking lots of questions. In this case, I'll usually make sure they get it and take my chances on the dynamism front.
Not all of my observations were positive: some basically amounted to the two of us disagreeing. One particular observer thought translation should never be used in class. I thought that was ridiculous. The other day in class we were talking about food and the word “rosemary” came up. I didn't know how to explain it beyond saying it was a spice. It just makes sense to translate it as “romero”. This same observer also didn't know much about the Lexical Approach and favored PPP (Present, Practice, Produce). So we were on different wavelengths and really didn't have much to say to each other.
I remember I once told a friend of mine, a free-lance teacher (who doesn't work in an academy), that I was going to be observed, and he said he envied me. That surprised me because I was feeling nervous about it. But he was right: being observed has clearly benefited my teaching. So I'm in luck: I'm up to be observed soon!