Unlike big companies where you work as a corporate cog and get the salary pertaining to your level, if you are planning to work for small to medium companies, chances are that there is no set levels for salary. So, you need to mind a bit of salary negotiation tactics in order to get the best deal. Couple of rules might help your salary negotiation:
Information is key - you want as much as possible, do your research and ask the company a lot of probing question. Knowledge is power, and you need to understand what their position is.
Understand where you draw the line - if you need 24K to pay rent, loans and eat, you can't accept less no matter how much you want the job. Know what you have to have and be prepared to walk away. Research the word BATNA, this is very important.
Don't focus on single issues - salary is one issue, but perhaps creativity can help you get more value from the relationship. Say if you want to join a fast food startup and the employer has a rental properties...hmmm, as for 2 meals a day and an apartment to be thrown in, you can take a lower salary and both parties win.
Let them throw out the first offer. It may be higher than you expect, and then you can negotiate for even a bit more. If they lowball, you can explain why the offer is too low and counter with a high offer, expecting to meet closer to the middle.