This method isn't very sophisticated, it's based on a very simple logic and works 90% of the time.
What we're going to do is, to delete every message that contains the word subscribe in it; Since all the advertising and spamming mails contain this word.
In case you are subscribed to some important mailing lists, you might want to not delete it. You could make it skip the inbox and forward it to a label that you create.
So to create a filter on Gmail, go to settings>filters>create new filter.
We want to apply the filters on every message that has the word 'unsubscribe' and this filter should delete this message.
I hope this was useful, and be careful while applying filters.
