since I am new to Manual Testing I don't have much idea in drafting test cases.How many test cases can be prepared for a text box field which has to accept 0-3 number as per specification.My idea is to write test cases like Enter less than 0 in the Text Box,Enter 1 in the Text Box,Enter 2 in the Text Box,Enter 3 in the Text Box,Enter 4 in the Text Box(Boundary value Check),Field level Check(Skip to next field(Null),Enter more than 1 number(Max length),Enter Special Characters(Alphanumeric Characters),Enter negative numbers in the text box,etc).So totally there will be 9 test cases.It will be helpful if anybody refered this answers.Thanx in advance
Sounds more like a test or interview question to me than a real world testing problem.
However, looks like you've given it some good thought so I'll offer one piece of advice - two of your tests are unnecessary. Look up "equivalence classes" or "equivalence partitioning". Suggest reading "Testing Computer Software" by Cem Kaner et. al. for more information.
If your developers are smart, they'll restrict the field length to 1-digit. This should hopefully elminate all potential negative entries as well as multi-character entries. Then, all you have to worry about is any single-character that can be entered or generated from the keyboard.
If you have questions about field-level validations, you should ask your development team how they are implementing these validations. Once you understand what they're doing, then you should have a good idea on what to test.
A chapter from my "lessons learned":
I once tested a product that had field lengths restricted at the UI level but not the database level. I was able to enter a 5 digit number in a 4 digit field - but the UI only showed the last 4 digits of my 5 digit number.