Um well, assuming you are current, you really should know the answer - engines do really stop sometimes.
Are you doing your FI rating in Malta, or elsewhere? I guess the detailed answers will depend on local landscape. But basically I like to go with all the S words:
Size - is it big enough
Shape - round or square better than long and thin (gives more approach options)
Slope - flattish (land up hill if you have to land on a slope)
Surface - smooth as you can and short crop if possible, tractor wheelings roughly into wind so you can land along them
Stock - no animals
Shocks - no cables in field or on approach
Surroundings - some civilisation nearby so you can get help
and before you worry about any of these, only look at fields that you can be sure of reaching (know the glide performance of the aircraft, what the wind is doing and how high above the ground you are when the engine stops). Remember that a good approach into a poor field is better than a poor approach into a good field.
hope this helps
H