The document outlines 4 common pitfalls of project estimating: 1) Not allocating enough time to properly estimate which can lead to inaccurate estimates. 2) Not managing stakeholders' expectations by explaining that estimates evolve over time and when more accurate numbers can be expected. 3) Being too specific in early estimates since specific numbers do not necessarily mean accurate. Ranges are better than single point estimates early on. 4) Being over-optimistic and not realistic about what can realistically be achieved given potential challenges or delays. The document recommends allowing sufficient time for estimating, using ranges instead of specific numbers early on, regularly updating stakeholders, and planning estimates based on a realistic assessment of potential obstacles.