Prerequisites for load Testing in load runner

Important Set up before load testing includes:

A suitable time to load-test the application, for instance when no development work is taking place on the server (load testing may cause the server to crash) and/or no other users are accessing the server (else the testing results would not yield the correct measures)

1.  The performance metrics, accepted levels, or SLAs and goals
2.  Objectives of the test
3.  The Internet protocol(s) the application is(are) using (HTTPS, HTTP, FTP, etc.)
4. If your application has a state, the method used to manage it (URL rewriting, cookies, etc.)
5.  The workload at normal time and at peak time
6. Before load or performance testing application should be stable at least tested at once through the manual method
7. Before load testing, do not record any page, which has 404 or server errors
8. During load test don’t do real transaction or any money ready work.
9.  During load testing try to maintain the real scenario as user experience
10.  Use meaningful test scenarios (use cases are helpful) to construct test plans with 'real-life' test cases.
11.  Make sure that the machine running Load testing tool has sufficient network bandwidth, so the network connection has little to no impact on the results.
12.  Let Load Test run for long time periods, hours or days, or for a large number of iterations. This may yield a smaller standard deviation, giving better average results. In addition, this practice may test system availability rate and may highlight any decay in server performance.
13.  Ensure that the application is stable and optimized for one user before testing it for concurrent users.
14.  Incorporate 'thinking time' or delays using Timers in your Load testing scenario Test Plan. 
15.  Keep a close watch on the four main things: processor, memory, disk, and network.
16.  Only run Load testing tool against servers that you are assigned to test, else you may be accused of causing DoS attacks.