I have a major problem of figuring out in sentences wether a preterite congugation goes there or an imperfect congugation goes there. Is there any way to help choose which one? How do you know what to use?

Well, there are lots of rules for preterite and imperfect to find on the net. Even though I have read them I still find it hard sometimes to choose so I understand you. You can look at these links, maybe they help you a bit on the way.

http://www.forodeespanol.com/Archive/PreteriteAndImperfect/ckw/Post.htm

http://www.forodeespanol.com/Archive/PreteritoImperfectoEjercicio/cbxg/Post.htm

http://www.forodeespanol.com/Archive/PreteriteVsImperfect/bwnj/Post.htm
Well, the simplest rule there is, is the following:

1) You use Preterire for actions that happened and finished in the past - so preterite is the equivalent of the simple past in English

2) Imperfect in Spanish is the equivalent of the past continuous in English, which means that any action that had a period of duration in the past and that did not happen only once will be expressed with a countinuous tense, i.e. with imperfect. The key is DURATION.

- You use Imperfect for actions that happened AND LASTED FOR A PERIOD OF TIME in the past

"The phone was ringing" (a countinuous action in the past, it kept ringning and ringing)unlike preterite "The phone rang" (it rang one time and stopped, no duration in the past)

- for actions that were habitual in the past (and that were usually annoing)

"Ella se cuejaba siempre" - She was always complaining"

- when you are narrating something, telling a story or describing an event:

"Era una mujer muy linda, tenia ojos ...."

- for an action that was in progress when someting else happened:

"I was talking to Maria when he came into the room". - "(Yo ablaba cuando el entro..." - "was talking" is something that had a period of duration in the past, while "he came" is an action that happened only once in the past and lasted a minute, there was no duration in the past)

- for 2 simultaneous actions that happened and lasted in the past:

"I was cooking while she was cleaning." - "Yo cocinaba mientras ella limpiaba" (for both cooking and cleaning you need time, they are actions that lasted in the past)

I don't know whether I expressed myself clear enough, but hopefully it will help.

Ciao
I found this very helpful [F]
http://www.studyspanish.com/tutorial.htm
MaltaI found this very helpful [F]
http://www.studyspanish.com/tutorial.htm
It sure is a helpfull site [Y] I still use it.
I like the excersizes.
you just have to look at what the sentence is saying. preterite is the completion of an action and imperfect is continuing or habitual action. just read it and see what makes sense
i have no clue buddy i'm in the same dang boat as you.

I am a spanish teacher at Glastonbury, CT high school.....

you can use both of the tenses for the past. you use imperfect is used for ongoing or repeated actions. The preterite is used for actions that have already been completed in the past. It can also can describe how a person felt about the past.

i hope this has been helpful! Good luck in the future useing preterite and imperfect! Emotion: smile