A: This is probably a bad idea. Please read the explanation below. If it still seems like a good idea, please follow the directions at the end to give us a better chance of coming up with a satisfactory translation.
To begin with, if you think a phrase that is pithy and clever in English will become more pithy in Latin, you are incorrect. If a phrase sounds great in English, then it's making use of unique attributes of English. A Latin version will have to make use of phrasing that doesn't match the style or doesn't match the content.
It's very tempting to treat Latin as a code, something you can convert English to and from without any loss of meaning, but that's not the case. Translation is much like a game of Telephone, or even Telephone Pictionary, where the meaning becomes more garbled each time it goes through the process.
There is also the cultural context of a phrase to consider. When something is written in English, a reader will assume that the phrase comes from modern English-speaking society. A phrase in Latin will be assumed to originate in Ancient Rome, or at latest, from the Renaissance. This will confuse any readers.
Keep in mind that there do exist people in the world who read Latin better than they speak English. Someday you may meet one, and find yourself explaining the difference between "lousy" and "covered with lice." (This has happened to me with a T-shirt.)
In the same vein, it's not a great idea to have something permanently inscribed on your body in a language you don't speak. Especially if it's not recognizable as a motto, it acts as a (misleading) advertisement for your skill in the language.
There is also the danger that whoever translates it for you does a poor job, intentionally or not. It is entirely possible to translate something literally and end up with a very different idiomatic meaning.
Q: But I'm planning to put the tattoo in a, um, private place. So I don't have to worry about this, right?
A: I submit that this may not be the best way to find out that a new friend is a Latin scholar.
Q: So what should I do instead? I want something that looks mysterious!
A: You have a number of options. You can use an odd font, or some different way of writing English. You could do a lot worse than Shavian, an alternate script for English funded by George Bernard Shaw's estate.
Q: So if I'm still dead set on getting this phrase translated into Latin, what do you need?
A: If it's a quote from something, please provide the context! This goes a long way toward determining how to translate English words with many meanings. If you can identify the exact meaning of all of the ambiguous words in the phrase, that is also useful. And be prepared for an iterative process. We're likely to ask a fair number of questions.
Please comment if you would like to add information to this.
ETA: People occasionally ask about phrases that were in Latin to begin with. These are significantly safer, though it can be worthwhile to have a Latin scholar glance at it. The same applies to a phrase that has a "standard" Latin translation, in particular any quote from the Bible.
ETA: If you're posting a question you want an answer to, make a new post to this community, which will be seen by all the members, not a reply to this post, which will be seen only by the author.