Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

"I ate the whole thing!" (25 points): Complete all four restaurants in Flo's career.
"I really ate the whole thing!" (55 points): Complete all four restaurants in Flo's career with all expert scores.
Endless, Schmendless (10 points): Last 10 minutes in single player Endless Mode on any difficulty.
There's always tomorrow Flo (3 points): Lose all your stars in Endless Mode on any difficulty.
Now we're cookin'! (7 points): Earn Five Stars over the course of Flo's career.
That's what I call an upgrade! (5 points): Unlock the full version of Diner Dash.
That's what I call team work! (15 points): Win 10 online Team Dash games!
There's no time like the present (15 points): Win 10 online Time Wars games!
Here's a tip for you... (15 points): Win 10 online Tip Wars games!
Will Flo please stand up?! (15 points): Win 10 1v1 Head to Head Games!
Workin' nine to five... (20 points): Win 20 Team Dash Games with at least three other teams.

Additionally, there is one secret achievement:

Secret achievement (15 points): Unknown.