Cost estimation typically starts with breaking the WBS into priced components (bottom-up estimating) or comparing to a similar past project (analogous estimating); bottom-up is more accurate but takes longer. Resource planning means matching the right people, equipment, and materials to each task at the time it is needed, avoiding both idle resources and bottlenecks where one person or tool is overbooked. Experienced project managers add a contingency reserve -- commonly 10 to 20 percent of the budget -- to absorb unforeseen costs like price increases, exchange rate shifts, or delays, which is especially important when budgeting in naira for materials or software priced in dollars. Without a contingency buffer, even small surprises can force a project over budget or into an unplanned pause.