Think about the different pieces of the pie.
1. Amount per hour
2. Amount per project
3. Location work needs to be completed
4. Deposit
5. Payment terms
6. Time to finish the project
7. Specs and reporting

All of these can help you negotiate their rate. The important part is to ask up front what they expect for each one of these, then ask of there's a part, if made more interesting can help reduce the rate (ex: 50% up front, or Net 0 vs. Net 30, etc)

You just want to ensure they do make some money so their invested in your project - you don't want someone working for you who doesn't want to be there.

Hi!

I have been working with freelancers for a while. Hope there tips help.

Start by considering these:
- always fix a price before starting a job
- leave most of the price to the end subject to results
- try to define a worksheet with predefined formulas so you just have to input the parameters and the totals are according to what you agreed
- make a table to define an schema of more work, less cost by the hour or unit
- define a confidential and non disclosure agreements before you begin
- arrange the way you are going to proceed in special situations like ending the job before it is completed

If you're buying freelance or contract services, the most important thing is the preparation you do beforehand. Getting a very clear scope and very clear requirements does two things -- first, it lets you know if you can afford to go cheaper (for instance, outsourcing to Eastern Europe or the Philippines) or if your requirements call for someone who is top-notch at what they do. Second, and more importantly, any freelancer/contractor much prefers working with someone has a clear set of requirements and knows what they want. When you're very clear and come across easy and pleasant to work with you, you can get preferred rates. I've got a lot of experience both as a buyer and seller of contract/freelance services, so do follow up with me for a call if you're interested in fleshing out a gameplan for your particular situation.