Uldah has the best r40 battlecraft leves and some good r30s. Limsa and Grid has good leves as well but with the current leve system it is easier to find people to have similar leves in Uldah therefore you never have to leave Uldah.

1-15 kill random stuff

15-25 Horizon Behest

25-30 Kill ants in copperbell

30-50 do the same 6-8 leves every 36 hours

44-50 kill raptors in coerthas *optional