What are the benefits of attending international conferences at student level
It is hard to tell - it depends on the conference! 

Possible benefits (amongst others) can be:


Learning more about your field and getting more motivation for your studies
Learning about different countries and cultures
Learning how scientific conferences work
Preparing your own scientific contribution for a conference
Networking with well-known people in your field (usually there are some invited speakers)


I would strongly recommend to submit your own contribution to such a conference in order to participate fully. 

For the "tips"-section:


Hang out with people you did not know before
Find a good mixture of new / unknown topics and things which are close to your fioeld of interest
Attend every social event
Don't hesitate to talk to foreign people.