Step #1 Rotate engine to TDC. Piston #1 should be at TDC.

Step #2. Check timing marks at the camshaft sprocket and crankshaft sprocket. Check manufacturer's instructions.

Step #3. Use camshaft sprocket holding tool as necessary but not required.

If compression is low (only for interference engine) after replacing the timing belt or chain, tensioner, pulley etc.. most likely valves are bent.

In this video I explain what happens when your timing is off by a tooth or two. If timing is off, you may experience engine misfire, poor engine performance, low power, idle issue, stalling and weak acceleration.