A tattoo is a form of body modification where a design is made by inserting ink, dyes and pigments, either indelible or temporary, into the dermis layer of the skin to change the pigment. The art of making tattoos is tattooing. Tattoos fall into three broad categories: purely decorative (with no specific meaning); symbolic (with a specific meaning pertinent to the wearer); pictorial (a depiction of a specific person or item).
If you definitely know that this female will use your beauty services in sinful way, then you should not help her in doing wrong. If you do not know that and they do wrong later on, you will not be responsible of their sinful acts.
We are not allowed to touch Quranic words or even letters with out ablution. When tattoo is on your body with Quranic words, you must remain always with ablution which is impossible because you need to go to the toilet and sleep etc.
Men should avoid showing tattoo on their body to non Mahram women when there is a possibility of bad effect.
Tattoos are allowed as far as it is a color which does not prevent water from reaching to the skin. Females should not show their tattoos to non mahram men.
Thank you for your question. There is no problem in getting a tattoo on your shoulders.
May you always be successful
There is no difference between the well recognized Maraaji’ of Taqleed on the permissibility of having Tattoo. All of them say that it is permissible as far as it does not contain Quran or holy names of Allah and Infallible, and it should not be shown to non Mahram man if it is on female.
I have not seen a fatwa which explicitly prohibits tattooing. However, one has to be careful what picture or image will be tatooed. Anything which is immoral or with sexual connotations will, of course be haram. Similarly, it has to be remembered that praying with clothes which have images on them is makruh. One could possibly extend this ruling to cover tattoos also. My personal advice would be not to undertake this practice which has no Islamic basis. May Allah (SWT) guide us all.