Hold two whole loaves during Hamotzi. Precede with “Birshus rabbosai… “ since you should be motzi others in the beracha. (ShA1 – MB 2,3)
On Friday night only do you eat the bottom loaf. Position it forward closer towards you than the top one so that you won't have to be maavir al hamitzvos. At all other seudos, cut the top loaf. Some poskim (Gr”a) hold to cut both loaves each meal. (ShA1 – MB 2,3,4,5)
If you don’t have two whole loaves, you can fulfill lechem mishna with part loaves. (MB2)
Medakdakim are careful to mark the loaf to be cut with a knife. Do not cut into the bread until the beracha is finished. (MB5)
Show your endearment for the mitzva of eating Shabbos food by cutting a big slice, enough for the entire meal. (ShA 2 – MB 6)
All should wait for the botzaya to eat the bread before tasting their own piece, unless they have their own lechem mishna (and the botzaya merely said the beracha for them). (ShA3)
The first two meals of Shabbos must consist of bread. (ShA 4)
If you have an oness and cannot have a whole meal at night, at least recite the Kiddush and have a kzayis of mezonos or r’viis of wine. You will have three meals during the daytime. (MB 9)