When you talk about seeing someone or something; watching TV, movies, plays, or sports; visiting someone or a place; possible results; or want to indicate understanding, go with ver. If you talk about paying attention or asking for someone's full attention or awareness, go with mirar.
For exp, I am watching TV. Watching is a continuous verb. If verb + ing adds information to a noun or it shows parallel action of the subject, it is called a present participle. For example, I slept watching TV.