It is ossur to cut hair or nails whether they are yours or your friend’s and whether you cut them by hand, teeth, or utensil.(ShA 1 – MB 1)
Cutting hair or nails with a utensil is deoraisa.(MB 2,3)
A woman who forgot to cut her nails in preparation for a Friday night mikvah should ask a non-Jewish woman to cut her nails. If she cannot manage by hand, she can cut them with a utensil. It's another case of shvus d’shvus b’makom mitzvah. If there are no goyim available, the woman can be lenient to scrape the dirt from under her nail.. She should look carefully to make sure that no dirt remains.(MB 3)
If the above oversight was regarding toenails, scraping away the dirt is preferred to a gentile cutting the nails.(ShaH 3)
It is forbidden for a man to pluck white hairs from his black hairs in order to look younger. This is what women do and therefore included in “lo yilbash gevver simlas isha” , even during the week.(ShA 1)
The issur Gozez includes plucking hairs or lice from fleeces and hides. Plucking feathers from chicken is likewise prohibited whether dead or alive.(MB 4)
It is forbidden to pick, bite, or cut off a wart from your body on Shabbos. This is true even if it has dried and is about to crumble by itself. This issur also applies to strips of skin hanging from your fingers, lips, etc.(ShA 2 – MB 6,7,8 – BeH “yabelles”)
Erasing or scraping off letters or blotches of ink from parchment, paper, wood etc. is the melacha of Mochake. Scratching away wax drops to reveal writing is also ossur.(ShA 3 – MB 9,10)
There are three melachos that are only chayav if you do them “al m’nas…".They are – Erasing (Mochake) in order to write, Demolishing (Sosair) in order to build, and Tearing (Koraya)in order to stitch. The intention to write, build, and stitch does not necessarily need to be on Shabbos – intending to fulfill these conditions anytime in the future makes these melachos chayav.(MB 13)
If liquid falls on top of writing, do not lick it off or rinse it with water. Even though it has not yet dried, it is still subject to Mochake. We do not consider it merely covering the writing.(MB 13 -ShaH 18)
Do not use a piece of wax as a bookmark. There is concern for Mayruach.(MB 13)
You are allowed to cut a cake made into the shape of letters. However do not break letters written on the cake.There are those who are stringent not to break decorative pictures either. In any case, you are allowed to give these cakes to a child.(Rama 3 – MB 14,15,16)
Breaking letters or pictures with your teeth while you eat is permissible.(MB17)
It is recommended to refrain from writing on the page-edges of a closed book since there are poskim who forbid opening it and closing it on Shabbos. It is proper to be machmir where possible. However, if no other similar book is available, the custom is to be lenient, relying on the Rama and many achronim who compare it to opening and closing a door.(MB 17 – ShaH 25)
Are you allowed to write with your finger? If you dip your finger into a drink and write letters – no. Writing on a fogged window – no. Drawing letters in dry sand or ashes – no. If you just motion the shape of letters in the air or on a dry surface – yes. (ShA 4 – MB 19,20)
It is forbidden to go to a gentile's house to learn a craft on Shabbos. However, if by chance you see a gentile doing a craft you are allowed to watch and learn – just be careful not to speak about it with the gentile.( MB 21)
It is forbidden to write on your skin on Shabbos. (MB 22)
Combining (e.g. plastic) letter shapes is a type of Kosave. Separating them is a type of Mochake.(MB 22)
You aren't allowed to scratch a mark with your fingernail in a book to remember something (e.g. a mistake). (MB 24,25)
If a thread comes loose on a seam do not pull the thread to tighten the seam – it's the melacha of Tofair. Tearing a garment at the seam is Koraya (ShA 6 – MB 26,44)
Some garments are fashioned with a pull string to tighten the end of a sleeve. It is permitted to tighten and loosen those strings. It is not similar to Tofair since the eyelets are wide and reinforced. This feature makes it easy to loosen and tighten all the time. However, do not pull and tie it on Shabbos to a semi-tightness that you will keep forever. (ShA 7 – MB 28,29)
Do not stuff a pillow for the first time on Shabbos – it’s tikkun kli. However, if some stuffing came out of the pillow you're allowed to put the stuffing back in – just be careful not to stitch it up. (ShA 8 – MB 33)
Products of the earth like fruit, vegetables, wood, and grasses may not be gathered from where they grew on Shabbos, even if they are already detached from the ground before Shabbos. It is the melacha of M’amayr. Fruit that was scattered inside the house is allowed to be gathered. (ShA 9 – MB 37)
M’amayr also includes stringing figs to bunch them together. This applies likewise to any product which is bunched up to be one unit (compare garlic). You would be chayav even indoors. (ShA 10 – MB 38)
Breaking off a useful piece of pottery or paper is ossur because of tikkun kli. (ShA 13 – MB 40)
Tearing paper for wiping or any other use is the melacha of Koraya. (MB 41)
It is forbidden to tear open a sealed envelope even if you avoid breaking letters. In great need, you may instruct a gentile to open the envelope. The Agudah writes that you should hint to the gentile "I cannot read the letter as long as it is not opened" – and if the gentile understands on his own and opens it – no problem. (MB 41)
Gluing together paper, leather, or even wood is a type of Tofair. Pulling them apart is a type of Koraya. (ShA 14 – BeH “haray”)
If (e.g.) wax dripped onto pages and stuck them together, you can separate them. They aren't considered stitched together since it was not permanent nor intended, therefore tearing them apart is not considered Koraya. However, if the (e.g.) wax fell on letters it is ossur to separate them because of Mochake. See above ShA 3. (MB 45)
Defective pages of a book that were not cut from before Shabbos are forbidden to be torn apart. (MB 45)
If a garment got tangled in thorns, remove it gently and discreetly. If it tears it's unintended. (MB 45)