1. He should be Explorer.
2. He should have the desire for the Quality.
3. He should be able to present the customer's point of 
view.
4. He should be deplomatic by nature so that he can make 
good relationship with the developer.

They should be familiar in sdlc.
they should be tactful mind
goodjudjiement skills
always ready to new techinal skills.
quality oriented mind.
always try to break the system.

A good tester has these qualities :
1.Methodical and Systematic .
2.Tactful and diplomatic .
3.Sceptical, especially about assumptions , want to see 
firm evidence .
4.Able to notice and pursue odd details .
5.Good  written and verbal skill .
6.A willingness to get one's hand dirty in order to try 
something new .
7.Able to swiftly understand the nature of business .

unless developer challenges break my code and tester says i
found bug there wont be quality product released out

a good tester should have the fallowing qualities

1) understand the design thoroughly and anticipate where he
could find flaws

2) should have multi dimensional views, play with the
software in all angles with all perspectives

3) should write robust test cases, all weired one so that
none of the bugs passes 

4) should keep track of all the bugs raised and  
suggest,fixing right CR's based on the requirement which
will help minimize the the failure rate at right time

5) should think and anticipate the bugs in advance and find
them during the design phase itself which reduces time in
finalizing the design

many more qualities are there but not enough time to write
have to get back for the work please correct me if my point
of view is wrong im still budding flower in this profession
:-))

good aptitude skills
creativity thinking 
good analytical skill
prepare test case
design test case
execute tect case
prepare bug report