Should I study in Dictionary form or Polite form

Hey guys, I have been reading on these forums for a couple of months now as I started studying Japanese at college earlier this year.
In class we have been covering basic grammar such as where we live, what we like to eat etc, Lately we have been looking over the (Dreaded) て Form which, thanks to my teacher, wasn't that bad.
Obviously everything I have been learning and studying (vocab) has been in the polite form. My teacher commented that we would learn some of the Plain form closer to the end of the year.
I also noticed in the Beginners Oxford Japanese-English dictionary that I got last week (really is a great study aid) that there is quite a big distinction between the Plain form and the Polite form and also the basic Dictionary from.
Should I study my vocab in Polite form (What we are doing in class) or Dictionary Form as to gather a better basis of understanding for moving onto plain form?

I don't know what the distinction between "plain form" and "dictionary form" is. I always thought they were two different names for the same thing.

At any rate, you're going to need to be familiar with all forms. Fortunately, the only thing more regular than Japanese verb conjugation is an atomic clock, so it really isn't all that burdensome. Unless you're in a major hurry, just go along with the class and pick up stuff as it is presented. There is plenty of time to worry about other forms when the curriculum gets around to it.

Learning the polite form first will allow you to construct basic sentences quickly that don't sound rude - and the -masu form is a little easier to learn than the plain form initially.
I am teaching myself, I learned the -masu form first, and it allowed me to pick-up on patterns that have proven useful as I have progressed to more advanced topics. For instance, the polite positive past form is -mashita (tabemashita, ikimashita, etc.). And the plain positive past is the -ta form (tabeta, itta, etc.). Interesting how they both end in -ta... (check out the past forms of adjectives...)
I suppose you could pick-up on this pattern at any time - but I do think learning the -masu form first is a good idea - and hey, it takes like 4 minutes. Then move on to the plain form - I would and did learn it in this order: -masu form, -te form (and -ta form), plain form, then all others (potential, conditional, imperative, etc.).
But Mike is definitely right (he always is BTW), you'll eventually need all forms, and instructor's lessons (and most texts) are very well planned and tested - so just enjoy the ride!

Good question.

From my experiences, most classes or textbooks will teach using polite forms or -masu forms as the basis of learning. You'll learn how to speak nicely and politely from the beginning, but if you want to chat with friends or random people on the street, you'll come off a bit formal.

So plain or dictionary forms are nice as they are more useful in casual or everyday conversation.

Conversions from dictionary or plain to other forms follow the same logic, so I don't think it really matters. In the long run, you need to see the greater picture as in a revolving 5-way system.

i.e.

遊ばない: do not play
遊びます: play (polite form)
遊ぶ: play (dictionary form)
遊べない: cannot play
遊ぼう: let's play

てform
び、み、に、 turns to んで
ぶ、む、ぬ turns to んで
(It's all the same.)

So rather than seeing the different verb forms as transitions from either dictionary or polite form, see those two forms as possibilities in the greater picture.

dictionary forms aren't just useful for casual conversation, they tell you exactly how to conjugate the verb for all its forms.

to help with the ~て form, ichidan verbs are all standard, and godan verbs conjugate as follows when they end with the following sounds:
うつるって、むぶぬんで、くいて、ぐいで、すして

Just a little something that stuck with me from my first Japanese class.

YOu must know both polite and dictionary forms! Other complex and important tenses are derived form the dictionary forms only!