Three quality sessions a week. One of them is a 40-60min. "long run" done at your easy pace. The other two are interval sessions (i.e. 6 x 200m at 800 pace, 200m jog, 4 x 400m/400m jog at mile pace + 4 x 200m @ 800m pace/200m jog). Once every two weeks, replace an intervals session with a tempo run. This can be a 20min tempo at "comfortably uncomfortable" pace (as in not dying/hoping it'll end, you should feel like you could've gone for another 30min if needed). More Tempo examples; 5 x 1000m @ Tempo Pace with 60 secs. jog, 3 x Mile @ Tempo Pace with 60 secs. jog.
The rest of the week should be easy jogging days lasting at least 30min (if that's too much for your current fitness, then take the day off or do a low-impact exercise like swimming, cycling, yoga, chores, etc.). If you have a race that week, do the intervals or tempo session as scheduled; in this case make sure the interval recoveries are increased to reduce the chances of being too exhausted (i.e. 4 x 200m @ 800m pace, 400m jog).
Here how this would look like (ST means a stride, as in a 10-15sec. acceleration done at roughly 800-mile pace with 20-30s walking/jogging recovery. They can be done at the end or in the middle of an easy run. They're not supposed to be difficult at all. I prescribed an amount to do, but if you start to feel exhausted then go ahead and stop. It's not about how many you do in a day as it is how many you can do consistently weeks in weeks out).
Week 1
Mon: 40-60 min. Long Run + 6 x ST
Tue: Easy Day + 8 x ST
Wed: 10min. E; 6 x 200m @ goal 800m pace, 200m jog; 10-20min. E
Thu: Easy Day + 10 x ST
Fri: Easy Day + 8 x ST
Sat: 10min. E, 5 x 1000m @ Tempo Pace, 10min.
Sun: Easy Day
Week 2
Mon: 40-60 min. Long Run + 6 x ST
Tue: Easy Day + 8 x ST
Wed: 10min. E; 6 x 200m @ goal 800m pace, 200m jog; 10-20min. E
Thu: Easy Day + 10 x ST
Fri: Easy Day + 8 x ST
Sat: 10min. E, 4 x 400m/400m jog at mile pace + 2-4 x 200m @ 800m pace/200m jog, 10min. E
Sun: Easy Day
Racing Week
Mon: 40-60 min. Long Run + 6 x ST
Tue: Easy Day + 8 x ST
Wed: 10min. E; 20min @ Tempo or 4 x 200m @ 800m-mile pace (It shouldn't be your race pace, it should feel rather relaxed, 400m jog) + 1 x 100m sprint/100m walk + 1 x 50m dash; 10min. E
Thu: Easy Day + 10 x ST
Fri: Easy Day + 8 x ST
Sat: Race.
Sun: Easy Day
(Another workout to consider using 10 days out from a goal race: 1 x 400m @ goal 800m pace, 2-3min. recovery, + 1 x 300m @ goal 800m pace).
Running more miles helps build the aerobic base, which will help you to maintain an aggressive pace and not burn out on the second 400m. The tempos help the body deal with lactate acid, the main enemy of the 800m (the burning in the legs), I hope this has helped, and thanks for reading. Best of luck.