Web applicatio testing 
web application shold have the following features like
1.Attractive User Interface(logos,fonts,alignment)
2.High Usability options
3.Securiry features(if it has login feature)
4.Database(back end).
5.Perfromance(appearing speed of the application on client 
   system)
6.Able to work on different Browers(Browser compatibility)
  ,O.S compatibility(technicalled called as portability)
7.Broken link testing
.........etc
so we need to follow out the following test strategy.
1.Functionality Testing
2.Performance Testing(Load,volume,Stress,Scalability)
3.Usability Testing
4.User Interface Testing(colors,fonts,alignments...)
5.Security Testing
6.Browser compatibility Testing(differnt versions and 
   different browser) 
7.Brokenlink and Navigation Testing
8.Database(backend)Testing(data integrity)
9.Portability testing(Multi O.s Support)....etc

very importenat tests are 

Performance Testing,
User Interface Testing,
Browser compatibility, 
Portability testing,
Database(backend)Testing are essentials

If you still have any doubt feel free to mail me at :  
rajendra_penumalli@yahoo.com
or call me:9885162742