Salary negotiation is most tricky part in joining any company, it requires home work following are few note worthy points.

What is the salary trend?
Do some research and have some kind of baseline in mind. What is the salary trend based on number of years of experience?
Discuss this with your friends.
Let the employer first make the salary offer. Try to delay the salary discussion untill the end.
If you are asked your expectations come with a figure a little high and say negotiable.
Remember never say negotiable on a number you have aimed for; HR guys will always bring it down. Negotiate on AIMED SALARY 1 something extra.
The normal trend is to look at your current salary and add a little to it so that they can pull you in.
Do your homework and be firm about what you want.
Do not be harsh during salary negotiations.
It’s good to aim high, but at the same time, be realistic.
Some companies have hidden costs attached to salaries.
Clarify rather than be surprised.
Many companies add extra performance compensation in your base salary which can be surprising at times.
Ask for a detailed breakdown.
Talk with the employer about the frequency of raises.
Get everything in writing and, look it over with a cool head.
Is the offer worth leaving your current employer?
Do not forget: once you have the job in hand you can come back to your current employer for negotiation.
The best negotiation ground is not the new company where you are going but the old company which you are leaving. So once you have an offer in hand get back to your old employer and show them the offer and then make your next move.
Remember somethings are worth more than money: Job Satisfaction. So whatever you negotiate, if you think you can get more, go for it.
All the best!