HI Christian, Unfortunately there is no rule about this, it's just something you have to learn through noticing the patterns when you are reading or listening. There are lists, like this one http://www.perfect-english-grammar.com/gerunds-and-infinitives-verbs-1.html and exercises in lots of places online. If you look for "verb patterns with ing and infinitive" you should be able to find plenty of exercises to help you practice this.

Hi! The -ing form (gerund) means the action is about to or is happening (most of the time). The infinitive with 'to' usually comes after the gerund. For instance: I am going to eat. Here 'going' shows that he is about to do something while 'to eat' is the infinitive form which is about to happen.