I've toyed with a variety of strategies over the years of how to keep track of my writing conferences. I know some teachers utilize their iPads, but I guess I'm just a fan of an old school strategy:
Using a notebook, I put tabs down the side for students, allotting 2-3 pages for each. I write notes in the front cover about who needs what mini-lessons and form flexible small groups from there.
I start the beginning of the year with them analyzing themselves as writers. When they meet with me for the first time, they share their strengths, weaknesses and about their favorite piece of writing.
I try to conference with a few students a day but I like my notebook strategy because I can easily share the data with my writing co-teacher. We can both hold conferences without having to worry about iPad passwords :)
Plus it's easy to see their progress over the year!