אין קונין בשר בפיסוק דמים לומר לטבח תן לי בסלע או בשתים וכן לא יאמר לו הריני שותף עמך בסלע אלא מחלק להם שלישיות או רביעיות כפי החלקים שדרך לחלק בעיר בלא פיסוק דמים ומביא שתי בהמות ויאמר זו כזו ולמחר שמין הנשאר כפי ששוה כך יפרע לו: הגה וי"א דדוקא ישראל לגבי ישראל שרי בכהאי גונא אבל ישראל עם עכו"ם אפי' בכהאי גונא אסור: [הגהות אשירי פרק אין צדין]:

One should not purchase meat with a fixed price, saying to the butcher "give me [meat worth] a sela or two." Nor should one say to him "I am a partner with you for a sela." Rather, he divides for them thirds or quarters according to the portions that are customary to divide in the city, without a fixed price. And he brings two animals and says "this one is like that one," and tomorrow they assess what remains according to its value, and that is how he pays him. Rema: And some say that specifically a Jew with regard to a Jew is permitted in this manner, but a Jew with a non-Jew, even in this manner it is forbidden. [Hagahot Ashiri, chapter Ein Tzadin]

It is prohibited to weigh meat, even in one’s home, to determine how much to cook. It is not even permitted to place meat in the cup of a scale to keep it from mice if it is suspended in the place where it is normally weighed. One may not even weigh one piece of meat against another piece of meat. It is permitted to weigh meat by hand by taking it in one’s hand and estimating its weight but a professional butcher may not even do that. If he is capable of cutting meat in the size of a litra or half-litra he may cut it in a normal manner without concerns.

It is prohibited to pierce a hole in meat so that it could be suspended but by hand is permitted. If the intent is to mark the meat it is permitted even with a knife

One may scald the head and feet [of an animal] and pass them through fire, but one may not plaster them with lime, clay, or earth, as this appears like tanning. And one may not shear them with scissors, as this appears like preparing for the sake of the hair.

It is permitted to salt several pieces [of meat] at once, even though one only needs one. Rema: And some say that this circumvention is only permitted before the morning meal. It is permitted to salt meat on a festival even though it was possible to salt it before the festival (Maharil and Terumat HaDeshen §80).

The custom is to remove forbidden fats and sinews on a festival, even if the animal was slaughtered before the festival. [And it is good to vary the procedure somewhat, if one can vary in some way] (Maharil and Terumat HaDeshen §84).