What can I do to improve my team?

Hello, I am new to the forums, but I've been playing Top Eleven for a while; I'm currently on level 9 and season 9. I've done pretty good until now, well mostly in the League. I've always had first place, except for two times where I was on vacation and my activity had to drop from the game and now for some reason, as I currently am on the 4th position and it doesn't look like I'm going to be getting first place. I've been mostly losing and drawing to teams that are much weaker than me; I don't know why. I've always used simple tacitcs, such as 4-4-2, 3-1-3-1-2, 3-5-3, 3-4-1-2. I don't change formations that often, maybe just switch positions with a DMC or AMC, but that's it. My team's average has never been under four stars in the beginning of the season, and by the end I always pass the fiver star marker. For example, I currently am on five stars with a 61.8 quality. I do buy a lot of players usually around the middle of the season, but I haven't purchased any tokens with real life money, just used ones I got from sponsorships and filling out surveys etc.

What's a good way to improve my team to do better in Champions League and Cup? If any questions are needed to be answered in order to help me, please ask.

Looks like I should cut it into questions to make it easier.

Is it okay to change/buy players often?
What's a good tactic to score as many goals as possible against a very weak team?
What's a good tactic to beat teams almost the same or a bit higher than you?
What are preferred settings/orders?

1 it's ok bro to buy and chance players often because when you promoted in another level all your players lose 1 star.so you should buy new players every season
2 i don't know very good tactics

Check out this thread u will get every single counter formation whenever u have match check your opponent's formation then use the counter formation. http://forum.topeleven.com/formations-tactics/18650-table-counter-formations-v2-0-formation-use.html