Identify the type of friction involved
Determine the normal force between the surfaces
Find the coefficient of friction for the surfaces
Use the formula: friction force = coefficient of friction × normal force
For static friction, use the maximum value: friction force ≤ coefficient of static friction × normal force
For kinetic friction, use: friction force = coefficient of kinetic friction × normal force
If needed, resolve forces parallel and perpendicular to the surface
Measure or calculate the applied force and compare it with the friction limit
Use the direction opposite to motion or impending motion for the friction force