how to start in high lvl area?

as the title says, i dont know what to do in a high lvl area? i got 2 grey portals, but som e lvl 13 greedy guy ruined that by killing my portals and made lvl 5 portal out of it...now i cant do anything in the game just hacking...wp pretty fun.

what i have to do now? how can i lvl up?