With the Goths your initial strategy should really be geared towards taking Constantinople, Thessalonica and Athens in the first fifteen turns or so - naturally you should do this as a horde. Once the first two are taken build forts at the bridges north of them, and you'll never have trouble from the other Hordes. Ever.

After that, consolidate, get an Alliance with the ERE, get trade rights with everyone, etc, and build up you forces for the next phase, which is a direct and prolonged assault on the WRE. You should be making 5000d per turn by now, so you know the score - build, conquer, advance. Ad infinitum.

Works for me on H/H.