'''Hiding on a toilet'''
The most obvious trick is to hide on a toilet. The conductors of course know this classical trick but it still works surprisingly well. You can decide if you lock the door or not. If the door is locked the conductor can see it and might wait until you get out. If you don't lock the door they are likely to pass you but other passengers might want to go to toilet as well. For that reason you might want to sit there with your pants down like if you'd be shitting. It might be wise to just go to toilet when they are controling and then get out of the toilet again. IF you stay for an hour on a toilet it might raise suspicion.
'''Hiding in a luggage compartment'''
It depends on a train but often fast trains have shelves for luggage. What you can do is to look for a shelve which is partly filled but still offers enough space for you to hide in there behind your backpack. It is of course not the most comfortable but it is not too bad either. It is actually quite fine. After you hear the conductor walking by and asking people for tickets you can get out again and take a seat.
'''Dancing around'''
The finest art of blackriding is to dance around the conductors. There are different dance styles and you can invent your own. You can pretend having a phone call and just pass the conductor while talking to a phone. You might also pass them with asking for a direction to a train restaurant. If the train has two floors well the conductor is in one and you dance through the other one...
'''Running around the train'''
When you see a conductor controling get out of the train and run around on the outside and enter the train again in the part which was already controled. In some trains conductors don't even look out of the train when it stops in a station. In other trains they do which can make it impossible or at least tricky to do this trick without them noticing. This trick is suitabe especially for regional trains with short distances between stops.
'''Short distance ticket'''
In some countries (Czech Republic, Slovakia, Poland, Hungary, Lithuania...) conductor usually checks everyone in the begining and then just ask for new passengers. So what you can do is to buy only a cheap ticket to one of the first stations and then stay in. They will remember that they controled you but not what was your final destination on a ticket. This trick would not work everywhere since in many other countries (France, Germany...) they control everyone not in the begining of a journey but at some random point during the trip.
'''Getting caught'''
If you get caught you can try to invent a story (oh no where is my ticket? I had it right in my pocket.) or you can also just admit to them that you have none. IF they ask you for ID you can say you have none and most of the time they just kick you out on the next stop and you'll take the next train. Sometimes they might want to call the cops to get your ID. Generally some people think that when you get caught it is better to speak with conductors in English even if you speak their language. They might think that you are just a random hobo passing by and they are less likely to bother giving you a fine. If it happens that you get a fine it is likely that it will never get to your home country since it is not so easy for them to get the money from you if you live abroad. Often times it is like that but there is no guarantee. Sometimes the fines actually get to you.