ファミマは英語の使い方に注意した方がいい。

Family Mart needs help with their English. Maybe you know how to become their consultant.

• 顧問 (こもん) (n,adj-no) adviser; advisor; consultant; (P);

If you do, you can give them this advice.

× Every Life, Every Fun
○ Fun for everyone! <- is this what they mean? I'm not sure...

I will admit that my version doesn't have the poetic repetition that theirs does. However, "every life, every fun" just doesn't make sense!

• 詩的 (してき) (adj-na,n) poetic;
• 折り返し (おりかえし) (adv) (4) repetition;

"Every" can only be used with singular countable nouns. "Fun" is an uncountable noun.

○ "We hope that the goods and services we provide will make your day a better and brighter one."

This one was correct. Good job!

× Let's go to Famima.
○ Come to Famima!

There are a few problems here. First, "let's" is wrong. It sounds like the Family Mart staff and I are going to go to another Family Mart together. That's just weird. This should be an imperative sentence.

• 命令文 (めいれいぶん) (n) (ling) imperative sentence; imperative statement;

I talked about "let's" back in April in this post. Please review:

http://upgradeenglish.blogspot.com/2009/04/dont-use-lets-if-you-are-giving-someone.html

Next, why should I "go" to Family Mart. I'm already there! To welcome someone to your place, use "come", not "go".

If you know anyone in a marketing department who wants to use English in their marketing, please recommend that they study with me!