Is there an easy way to answer questions about oxidation and reduction?

YES! OILRIG stands for Oxidation is loss, Reduction is gain 

This means that when a chemical is OXIDISED it has LOST an electron and when a chemical is REDUCED it has GAINED an electron. An electron carries a negative charge, and so if an ion (which is a charged particle) has a negative charge we say it has been reduced whereas if it has a positive charge it has been oxidised. 

Take Potassium as an example. A Potassium ion has a charge of 1+. This means that it has LOST one electron and therefore we say Potassium has been OXIDISED.  

So, if a question asks whether oxidation or reduction has taken place.. simply look at the charge (has it become positive or negative) to work out if it has lost or gained and electron and then use OILRIG!