Готовить (imperfective verb) is for:
- Cooking in general (I never cook rice = Я никогда не готовлю рис); or
- The process of cooking (What are you doing? Cooking. Что ты делаешь? Готовлю).
Приготовить (perfective verb) means make something cooked.
- I need to cook rice = Мне нужно приготовить рис.
- Have you cooked your meal? = Ты приготовил еду?
- Have a rest, I'll cook the dinner. = Отдохни, я приготовлю ужин.
Note that "приготовить", as a perfective verb, cannot be used in present tense. The forms that look similar to those of "готовить" in present tense, for "приготовить" are, in fact, future tense.
- Он готовит = He is cooking.
- Он приготовит = He will cook (have cooked).
Most Russian verbs are in pairs of perfective and imperfective.
These are not exactly synonyms, rather forms of the same word. They are not pronounced the same, in "готовый" there is a "й" sound at the end.
Short forms are not used for every adjective. I'm not ready to provide you with a rule (being a native speaker, I just know what sounds right). Try searching "short adjectives in Russian" on Google.
The Russian for “we don’t get ready” and “we are not getting ready” is «мы не готовимся». The verb “prepare” can be translated as готовить only if it used as transitive verb (in other words, there has to be a direct object). Otherwise, the verb готовиться is used in translation.