U are talking about 4-1-2-1-2 narrow diamond, right???
It looks like this-
DL-DC----DC-DR
-------DMC-------
---MC------MC-----
-------AMC--------
---ST-------ST----

I can give u fair enuf advice on it as I played the whole og my last season with this formation and finished 2nd. First of all, u shud always use the formation which allows your players to perform to their fullest. I always like playing 4 defenders and had gud players in that position. My DMC was a gr8 5 starrer so it was obvious to make him play. Plus he cud handle my opponents AMC. One of my MC was a 4 star dribbler and other was another high 4 starrer. My AMC was high 4 star and I like AMCs as it is my favourite position and they score many goals. I had 2 gud strikers one either footed and other right footed. So I placed the right footed on the right and he ended up being my top scorer. The other striker took all the free kicks and penalties.
So, if u use this formation and have fast DL and DR, place them on red arrows. Let GK play his position and give ur Dcs and DMC blue arrow. If ur opponent has no AMC give ur DMC red arrow. If ur opponent has wingers, let ur DL and DR play without arrows. Give both ur MCs red arrows or let them play without arrows. Give ur AMC and Strikers red arrows. Play attacking against weaker teams( I play hard attacking) and defensive against stronger ones. Normal Tackling( if u have a defensive wall, u can play hard tackling). Pass through the middle and keep long passes. Press own half. If ur defenders are faster than ur opponents forwards, play counter attacks and offside trap.
Hope this has helped. If any experienced player finds me wrong, pls correct me.