Go to the Nether
Find a Nether Fortress
Look for the fortress in large open areas
Search along straight fortress bridges
Explore nearby corridors and intersections
Check for Blaze spawners and Wither Skeletons
Use the F3 screen to track your coordinates
Keep moving in one direction to cover new terrain
Mark explored areas to avoid backtracking
Search multiple fortress sections if one area has none
Use a seed map or structure finder if allowed
Repeat until you locate the stronghold-like fortress structure you need