1. Find a dual, start a solo round, making friends from people in your alliance, find out their active time of the day and if they suit your playstyle, ask them to dual with you the next round.
2. Don't set your expectation to be a strong offensive player if you don't spend gold. Those top player you are seeing use gold daily to NPC their resources in their cropper and rebuild the infrastructure in their capital immediately if they ever being attacked with catapults. Be a defensive player and contribute to your alliance, playing defensive isn't boring if you are in a strong alliance and constantly receive request to protect your offensive players.
REMEMBER: seeing enemy offensive destroyed by you and alliance mates' defensive troops in the report is completely as satisfy as crushing enemy defensive troops as an offensive player.
3. Build walls, it is extremely underated by new players. for quick summary, at lv20, Roman wall give you 81% def bonus, Gauls palliside give you 64% def bonus, Teuton earth wall give you 49% def bonus.
4. Praetorians are infamous for their defensive stat against infantry. However, Teuton's spearmen are the strongest per crop against cavalry. Try to have some teuton def players.