To translate your favorite words or names into kanji you need the katakana alphabet and some basic rules, because often it is difficult to find the right pronunciation of English word in Japanese. There are a lot of sounds, which don't have an equivalent in Japanese katakana so that they have to be built with combinations.

• For example there is no sound for L in Japanese, R is used instead.

• The sounds ti, fa, fi, va, vi do not excist either in the alphabet (チイ,  ファ,  フィ,  ヴァ,  ヴィ) are used instead.

Examples

Tina pronounced TIINA is written:

TI is built with チイ (chi/ti + i)
and ー(to expand the vowel)
+ NA ナ

Bob is pronounced BOBU:

BO and BU from the katakana alphabet
are just added to BOBU

Angela is pronounced ANJERA:

A+N (アン) JI+E becomes JE (ジェ)
and RA (ラ) is used, because LA does not excist

So you see it's pretty simple to convert a western name into Japanese katakana. Thus it is just one litte step to your tattoo with the name of your beloved partner oder child.

But it is extremly recommended to look for a professional translation before you get tattooed. Here you can find cheap and very accurate translation into Japenese and Chinese
 

Japanese Translation
Chinese Translation