(1) Is there a legal contract between the bidder and the coder? Just in case my delivery date extends, what happens?
Yes and no. For RentACoder.com you have to comply to the project's conditions that are in most case standards. Standard stuff such as intellectual property that you must give away to the company your work for. Obvious things like that.
(2) After delivery, payment reach without trouble or not.
RentACoder.com has an escrow service that limit the troubles. The company that post a bid request pay in advance. But you don't receive the money yet. If you don't provide the work as requested, the company can decide not accept your work. Then there is an arbitration service you can initiate where an arbitrator evaluate the situation and decide what to do. In most case, the process and decision is fair.
(3) In case the customer didn't find the project useful, then? Probably he might say that it is not useful to me and you return money. He might copy the source code and return another copy to me.
It's a risk yes, and very few do it. The arbitration service is pretty fair and will limit those behavior.
(4) What are further recommendations? How should I start?
Create an account, and start to bid on projects.
Give what customers want.
I have managed hundred of projects on the platforms you mention. Here is how I work, and I think that most people do the same.
I discard 9 or 10 bids from user with less than 15 ratings and if the average rating is less than 95%. I then filter on bid price. Sometimes, when I read a nice cover letter from a lower bid, I can decide to go with him. Sometimes in parallel with a higher bid (assign the same project to two different bidders).
I discard every bid with no personal cover letter. I've observed that no cover letter means in most time that he didn't read the requirements. It will leads you to failure.
I generally don't care of the location of the bidder. However, I require a good knowledge of English.
When you get a project, do your best to satisfy the customer. Don't start any new project until the previous one is done. Target high quality. If the customer is not satisfied, negotiate a refund.
You WILL face bad behavior and customers that will take advantage of you. But only at the beginning. As you gain high ratings, you will be able to bid higher and that problem will be less frequent.
- Bid lower than others bidders to increase your chances to get projects assigned. Explain why you bid lower
- Customer that take lower bids are the most difficult, so you will need to work harder than usual
- Always write a personalized cover letter that shows you know what the customer wants
- Don't hesitate to negotiate full refund if you think the customer is not happy
- Work on one project at a time. Or two maximum if communication with the customer is slow
- At the end of each project, add your success in your portfolio