it' quite simple, don't do anything wrong : uploading copyrighted material. adult content. don't spam. don't use bots. don't have full on commercial videos. don't upload duplicate videos. etc etc.
If your videos are being deleted - their not your videos. This tells me that you have been taking someone elses videos and posting them under your account. Good advice, expect the "uploading copyrighted material" part. It should read "Do not upload someone elses copyrighted material." All of my videos are copyrighted and watermarked with my website name. They also have a copyright logo watermarked the entire length of the video. Its ok to upload your original production and material that belongs to you, even if its copyrighted. Just do not upload someone elses material.