You never want to have 80 cards. You want to have 40-45 cards most of the time at the maximum. I'd advise looking at reddit, and the yugioh wiki to get some ideas for how to make your decks.  If you play the yu-gi-oh mud done by tspivey, ask on chat and we can try and help you out.

ah, so 80 is apparently too much, lol.
alright, I'll try to make a proper deck this time, haha.
but the card is waaaay too much, I am confuse which one should I choose.
is there a tips how one choose cards with different style of playing?

There are tons of different deck playstyles to choose form, you really have to just look at cards and see what type of deck you want.  If all else fails, use a structure deck!  But you can do something like an element deck, a certain archetype, certain playstyle...but really you need to pick something and just look at the card effects and build something.  Tons of resources on the net if you just google "How to make ___ Yugioh deck"