I think that accurately estimating IT work is a combination of experience, natural gift, and luck.  With natural gift (think, big picture vision) and experience as being the two biggest factors.  And your estimate can really only be as good as the information you’re basing it on…so that’s something to always keep in mind and take into consideration as you’re providing an estimate on a technical project (or any project for that matter).

via Avoid These Common Mistakes When Estimating – Part 1 | Project Management Tips || Project Management, Collaboration and Knowledge Management Blog.