What are the points to be kept into consideration while estimating the project?

Its like triangle --> (1) Available resources to accomplish the project.  (2) Requirements of the project (backlog).  (3) Time boundary.

Assuming scope is already known, other points to consider will be Time and Procurement method

1. Understanding the scope of work. 

2. Capability of executing if project is awarded. 

3. Raw material cost, Man hours, Overheads, contigencies.

4. Availability of raw material, lead time to procure raw material. 

5. List of sub-suppliers

6. Required lead time to execute the order.

Direct cost 

Indirect cost

Resources

Contingencies

1. Understanding the clients requirement.

2. Matching the solution as per required Specifition.

3. All scope considred to be mentioned very clearly in Proposal.

4. No exclusion or minimum Exclusion .

5. All Exclusion to be mentioned very clearly in proposal,

During Estimation one should always go up to the break the schedule to the maximum. We should mainly consider both SCHEDULE, PHYSICAL RESOURCES & MATERIALS required for the SCOPE of Work.  Also we should consider the Government Policies, Climate & Anticipated Risks on the Site.

The scope of the project, Time, Risk management

Understanding the technical specifications and the end client's budget is the most important aspect of estimation. Moreover, method of procurement and the contractor's quality of work is equally important aspect to be considered while estimating.