The problem with the dragon language is that there are not that many canon words. Using canon-words will end up with something complete difference, something like "give your all" "Ofan hin pah", which looses the symbolic meanings it had in english.

It is possible to use non-canon words, but you will never know how long the words keep excisting. Before 2013 it would have been, "Bo fah zein". Which is "Go for two", but can also be translated to "Go for worship". In 2013 they changed the word for "two" to "ziin", making it "Bo fah ziin".

On the Thuum forum they announced that they stopped supporting the non-canon words and wanted to start over. If this ever happens then we might end up with a third version.

Another thing to keep in mind is that the dragon language can be more then just a cipher for english. There is also a culture behind it. With "what would a dragon say?", or "what does it mean if a dragon would say that?".

Another option would also be to write the english words in dragon runes.

What is your motivation to do it in the dragon language? Personally I think something as permanent as a tattoo would require a very good understanding of what you choose to get tattooted.