What css properties you avoid building web pages for ie7? What you usually check first when you see page that does not render well in ie7?
UPD: as a programmer is not a designer usually, i think that it would be useful to collect short list of bugs which generate most share of failures, not going deep into css implementations. Programmer will never know all this staff.
Ie6 is leaving, Ie7 therefore is a most source of failures.
IE7 is already consistent with all common CSS style properties (which I would define as: colors/backgrounds & borders, font styles, and placement (margin, padding, spacing, wrapping)).
Now IE7 doesn't support CSS2 or higher, but I'd say it doesn't even matter because all main CSS rules as stated above are working well.
There is a great guide on CSS compatibility across browsers found on Quicksmode.
This compatibility table includes the following browsers:
Studying these tables and more importantly, understanding the browser differences will probably help you a lot and is probably worth more than listing a top 10.
A great book that explains a lot of in-depth CSS and the reasons why it is rendered differently across browsers is CSS Mastery. It is my single most favorite CSS book.