Making sure the wedge clips are fully engaged and open is the most important step. Using a VFL will definitely help. In the image below, the connector on the right has the wedge clips correctly seated. All the light is exiting window #1 closest to the ferrule end of the connector. The one on the left has the wedge clips partially engaged so light is passing further into the connector meaning the CAM is not fully open inside the connector. The stripped fiber will have more difficulty entering the connector and mating with the bare fiber section inside the connector. Re-seating the wedge clips (sometimes more than once) should result in the connector looking like the one on the right.