Can someone please help me to set up a good strategy

I'm afraid you're not going to get that handed to you on a plate because people are not going to give all their best tactics away on a forum where everyone can copy. Join a good guild and the more experienced players will help you learn.

Here's one tip for free though. Always apply your training points manually and consider which skills are most important for players in each position. For instance, who relies most on speed and who needs to excel at tackling.