PCB fabrication is a very complex process. You cannot entrust your PCB manufacturing needs to anyone but the best manufacturers in the industry. Even someone who is experienced in this industry could make mistakes while getting their PCBs manufactured with the help of a third party manufacturer.
Do not think that you need to manufacture your own PCBs. The biggest brands in the world do not have their own PCB manufacturing units. They get it done from the Chinese PCB manufacturing companies. If that is how the top brands handle their PCB needs then it should send you a loud and clear message. You do not want to channel all your attention on just a single aspect of your product. There are other dimensions to your product and if you are going to be weighed down by the PCB manufacturing segment then all the other aspects would suffer. You do not want to put your brand to such great disadvantage.
Sending your PCB production needs to a PCB manufacturer before screening their reputation and history would be an even bigger mistake. You do not want to take such risks either. Before you sign up with any manufacturer, you should get all the information about your manufacturer, their past projects, their total experience, experience that are specific to your products or niche, the companies that they have worked with and so on. All these will help you decide whether or not you should go ahead with a particular manufacturer.
The third mistake is to decide only based on the cost factor. There are so many manufacturers in China and you will be able to get as many quotes as you like to but getting the quotes is not sufficient. You need to decide which manufacturer to choose by paying attention to the other credentials. When you are comparing the quotes, it should be done among the top manufacturers that you have shortlisted based on their industry experience and based on their reputation in the industry.
Not sending your requirements to your PCB fabrication company in good time is a very big mistake. Even the best manufacturers in the world will need time to manufacture your PCBs. You cannot expect them to deliver overnight. Do not wait until the last minute to place the order. You know your production schedule the best. You should therefore make it appoint to plan these events carefully and send your requirements to the screened manufacturer. Allowing adequate lead time will enable your manufacturer to deliver good quality PCBs. If you force them to speed up the process then mistakes could happen during the manufacturing process for which you will end up paying the price.
All the above mistakes could easily be avoided. You just need to make sure that you are paying attention to all these factors before you get started and stay away from these mistakes. There are many good PCB manufacturers in the industry. You just need to be sure you are dealing with the right manufacturers.