How can I learn construction estimating?

Learning construction estimating is a very long and tedious process. That's why it is very rarely you can find an estimator who can expertly perform estimating job from division1 to division of the National Building Code. One of the basic is to start by doing the items that you can count like similar doors, windows, doors/.windows/cabinet accessories, toilet/bathroom and kitchen fixtures and so on. you must carefully read the list of specifications first prior to starting your work because not everything can be found on the set of plans. you must also know the actual quantities of materials/equipment time/labor manhour needed to perform one unit (ex. square meter, square foot, lineal meter,  lineal foot, cubic meter. cubic foot). This will be your multiplying factor once you done getting the total area, length or volume of the building components you are estimating for. you should also know the commercial length, commercial weight, commercial size per piece of each materials involved in your estimate. Some estimators don't bother to know this causing cost-overruns in their estimates. Also, a good estimator must know where he can make use of his wastage. for example short lengths of lumber can be used as bridging od form stiffener, etc. and maybe some short lengths of rebars or steel barscan be utilized as stirrups ot stiffeners. wastage that can be avoided if the estimator can find use for them.

please take a help of a friend who is good in estimation with regular site visits