Tradução - Latim-Inglês - Quidquid agis, prudenter agas et respice finem!

"Think of the end" sounds like you're talking about death in English - I don't know if it has this double meaning in Latin. Otherwise, maybe it would be better to say "think of the outcome".

P.S. I changed "well (or prudently)" to "wisely".

I understand "finem" as an apocalyptical warning, but I don't know the origin of the latin proverb. It certainly has the double meaning in Latin though.
"Think of the outcome" is by my opinion without support in the latin phrase.
"Wisely" is better than "well".... But prudentia is difficult to translate.

OK; I will leave it as it is now. Thanks for the clarification.