Cloud base 

Fahrenheit : temperature - dew point / 4.4

Celcius : temperature - dew point / 2.5

Altimeter (Standard is 29.92 inches of mercury, 15celcius, Sea Level)

Decreasing altimeter by 0.01 decreases altitude by 10ft  (this gives pressure altitude, density altitude is pressure altitude corrected for non standard temperature)

Standard Lapse rate 

Useful to calculate freezing level: 0c or 32f, combine that information with visible moisture and you have a better idea of where you might encounter icing.

2 degree Celsius per 1000ft or 3.5 degree Fahrenheit per 1000ft

If the temperature is given to you at a certain altitude, add that altitude to the calculation, for example:  6celcius at 2300ft, freezing levels will be 6/2 = 3, so the freezing level will be at 3000ft AGL or 3000ft + 2300ft = 5300ft MSL 

VOR : 

1 in 60 rule : 1 mile off course for each degree of deflection

Deflection gets smaller as you get closer to the VOR 

Example:  if you're 3 degrees off at 30miles, the deflection is 1mile / 2 - 0.5 mile, 0.5 x 3 = 1.5miles off course 

Distance to station based on time between radials 

(60/difference between radials)* time it took to cross radials 

VOR Calibration : dial the VOT to 180 TO, if you have a dual one, they should both read within 4degrees of each other