How to ensure load test execute successfully...

Good day

Trying load testing for an enterprise level CRM application with dotnet
technology
we provided hosted solution to our customer as we used in Amazon cloud

Here are my step which I planned initially
Our primary objective is to execute at-least three phase of load testing
with jmeter and compare the result
Please suggest

Case-1
Number of Threads (User) =50
Ramp Up Periods (In Seconds) = 120
Loop Count=1

Case-2
Number of Threads (User) =100
Ramp Up Periods (In Seconds) = 120
Loop Count=1

Case-3
Number of Threads (User) =125
Ramp Up Periods (In Seconds) = 120
Loop Count=1

My Test Plan--Please suggest if it correct

<http://jmeter.512774.n5.nabble.com/file/n5720436/test_plan.png>

here is my summary report after execute 125 user (Case 3)

<http://jmeter.512774.n5.nabble.com/file/n5720436/125_user.png>

Please share if you have any better way to evaluate load of our application