Quick answer: A good arrow sign makes the direction clear first. Then it adds one reason to care and your name. The arrow can't do its job if it's buried under a paragraph of text.
Give the arrow room
The arrow shape must stay clear and easy to see from the direction people are coming from. Don't let decoration soften or confuse the point.
Pick one thing to read first
Offer, name, direction, and action should not all fight for attention. Pick the one thing people must see first. Everything else supports it.
Use contrast that survives real conditions
Your colors and type need to work in sun, shade, glare, and motion. What looks good on a screen indoors is not a real street test.
Test it in the real world
Test the sign from a real distance, from each direction people come from, and for the time they'll actually have to look. Fix it if people miss the point.