so i´ve noticed, if you use commas/fullstops in turkish sentences the wrong way, it changes the entire meaning/concept of the sentence..

how do you know when should you put a comma/fullstop and how do you know if its correct or incorrect?

tesekkurler.

comma prevent mixing the meaning, misunderstanding.

a short sentence with full stop the end recommended; if not, at least use comma between sentences.

Oraya gittim, etrafa baktım, kimseyi bulamayınca geri döndüm. (Actually there are three sentences or sentence parts here)

When you take short breath while speaking, you should put comma while writing the same thing.

how do you know when should you put a comma/fullstop?

Commas and fullstops are not that different in Turkish compared to English. So, you probably already know a great deal. Don´t be too hard on yourself. Even Turkish natives frequently make mistakes.

Luckily I know exactly where to direct you, because the Turkish language is regulated by the government and the correct way to use punctuation is made clear:

http://tdk.gov.tr/index.php?option=com_content&view=article&id=187:Noktalama-Isaretleri-Aciklamalar&catid=50:yazm-kurallar&Itemid=132

The page is in Turkish. If you cannot understand it, guess what... You´d probably be better off studying Turkish rather than being concentrated on punctuation.

how do you know if its correct or incorrect?

You´d know. If you don´t, you might as well study other areas of Turkish, other than punctuation.

True, punctuation could make a lot of difference. But I´d say, don´t worry about this. Because such a situation arises rarely.

I´ll give you a few examples anyway and let´s see if you can see the difference in meaning.

First, and the best: 

"Oku baban gibi, eşek olma."

"Oku, baban gibi eşek olma."

("Eşek" means "donkey" but here, it refers to someone mentally equal to a donkey)

The first one means, "Go to school like your father did. Don´t become a dummy."

The second one means, "Go to school. Don´t become a dummy like your father."

The same could work with full stops too:

"Oku baban gibi. Eşek olma."

"Oku. Baban gibi eşek olma."

Or, another classic example is the dilemma of "adjective or pronoun?"

"Bu, oyuncağın bir parçası."

"Bu oyuncağın bir parçası."

First one means "this, a piece of the toy"

Second one means "a piece of this toy"

But like I said, you´ll come across this kind of thing quite rarely.

Bonus: Sometimes, there´s no way of discerning. The classic example:

"Balkona çık" > "Get out on the balcony"

"Balkon açık" > "The balcony is open"

No punctuation can help you here. Lucky we don´t have a balcony.

If you´re desperate to make yourself clear:

"Çık balkona"

"Balkon açık duruyor"

The most informative place for a comma in Turkish is after the grammatical subject. For two reasons I guess:

- the subject phrase may consist of several words, modifiers + head

- what follows the subject in transitive sentences is most probably the object which  -  if indefinite  -  has no marking either.