Here's the general definitions from the wiki page:

I have thought about it and I do have a certain strategy I play with, but I kinda fail to condense it into something specific and I don't think it works always and I also doubt its the most optimal.On a sheet of paper, the players each write a 4-digit secret number. The digits must be all different. Then, in turn, the players try to guess their opponent's number who gives the number of matches. If the matching digits are on their right positions, they are "bulls", if on different positions, they are "cows".

Any tips, resources would be helpful.