Samurai was originally one of the dominate classes in Japan, and Bushi who serves to senior aristocrats or generals at the time were called Samurai. 
Since the Edo period they came to be generally called Samurai who learned martial arts. 
After that, the word samurai changed into a ideological or conceptual one, and anyone could call themself a Samurai. 
There are various theories about the origin of the words of Bushi, so I will omit them, but basically it is a generic term for people who have mastered martial arts and lived solely on that basis. 
When you see in ukiyo-e that the men wearing kimono, armor or half naked are referred. Not all of them are collectively called a Samurai.
There are various male subjects in ukiyo-e, such as Sengoku Busho, Kyoukaku, Gouketsu, etc. Not only the Samurai. 
In order to distinguish them, it is necessary to know each name, historical background, story, clothes, family crest and composition that match each. 
If you make a mistake in this, they will no longer represent any one individual. 
As an exception, there is also a way to express as "Mitate" or "Yatsushi".
When you want a tattoo of a human shape subject, you can say "Jinbutsu" rather than "Samurai".
Jinbutsu is the general term for human shape subjects when discussing tattoos.
For example, the heroes of Suikoden is a Gouketsu, not a Samurai. Danshichi Kurobay is a Kyoukaku or Otokodate, not a Samurai. Watanabe No Tsuna is a Bushou and a Samurai. 
Basically, there is wide meaning in a Jinbutsu tattoo. However, each Jinbutsu have their own stories and their unique personalities. 
It's best to choose a Jinbutsu that you feeling of empathy for or you want to be like. Choose one that embodies a feeling you wish to emulate such as strength, kindness, etc. 
The Jinbutsu that you choose will give you the courage you need to move forward in your life.