Rather than following complex training programmes, I'm trying a "fire and ice" approach. In other words, I'm running one 5k race at the weekend as hard as I can, and then trying to fit in as many long slow runs as I can (typically about 2 hours+ at 05:30 - 06:00 km pace). This has upped my weekly mileage for last two weeks from 30k, to 70k.
The last four weeks of 5k runs have been 19:11, 18:48, 18:52 and 18:36. So it's coming down, but I only have about 8 weeks to go.
Next weekend I'm doing the Edinburgh Marathon (plan to run at less than 85% MHR throughout, so I don't do too much damage...)
Prince of Fatness
It's been inactive for a couple of weeks, but there is a thread on this topic in the main forums.
HobbyJogger & HobbyRacer
You could consider doing some speed sharpening training as you approach your goal 5K. I've read that minor speed improvement can be picked up relatively quickly not long before goal racing. But I'm far from any kind of expert.
It's a 5k. It hurt like hell...then I tried to pick it up. The end.