When retrieving data from the CRM webservice, part of the
RetrieveRequest-object needs to have the required columns specified. In
many of the examples this field is specifically set to the columns
needed, which is the most “correct” way of retrieving the data. However,
if you aren’t experiencing performance problems the easiest way is to
use the AllColumns-class.

In short:

RetrieveRequest retrieve = new RetrieveRequest();
retrieve.ColumnSet = new AllColumns();

This is probably old news to all of you who have coded a bit. But I
thought I might write a bit about it anyway, since not all people are
experts at birth.