Use the 'clock' method:
15 deg off=1/4 W/V
20 deg off=1/3 W/V
30 deg off=1/2 W/V
45 deg off=3/4 W/V
60 or more, use all W/V
Max drift is equal to W/V divided by your TAS in mi/min. So if you're doing 180KTAS, that's 3 mi/min. If the W/V is 30kts, max possible drift is 30/3 = 10 deg. Now apply clock factor as above; if the W/V is 210/30 and you're holding on 240 deg inbound, use 1/2 max drift and steer 235 deg inbound. Outbound use 3 times that, i.e. 15 deg and make your heading 075 deg.
Now try it bouncing around in a single engine aeroplane at 90 kts without a gyro compass, no autopilot and no co-pilot. At night and in IMC!
You can use a similar method to recompute your GS using (90-angle off) and the clock factor. So if the track is 060, TAS is 180Kts and the W/V is 120/30, your heading should be approx 070 deg and GS 165Kts.