How can I recognise transitive and intransitive verbs?

When reading, there are two main telling signs to look for:

1) An intransitive verb always takes the particle "ga". For a transitive verb, "wa" will be used almost exclusively, unless "ga" is used for emphasis of the subject.

2) A transitive verb will always have a subject, such as "watashi wa", and an object, such as "doa", and will use the particle "wo" before the verb, for example, "watashi wa doa o aketa". In contrast, an intransitive verb will only have the object, for example: "Doa ga aita"