How do I form the subjunctive?

I would first make sure that the student understands the situations when the subjunctive is used. If they do not fully understand I would explain that before starting.I would teach the student the 'swapped vowel' rule as it is relatively straightforward eg. They eat becomes coman instead of comen . Following this I would give them some simple sentences to translate using the subjunctive eg. I don't think its fair that they eat his sweets. After the student has completed some practise sentences I would introduce the irregulars.