Functional resumes are good when you have little to zero work experience (or new grads). This type of resume allows you to showcase skills that fit in with the job requirements. Fair warning: most recruiters and hiring managers dont like this format and feel as though you may be hiding something. If you have a chronological resume you do not want to have one part chronological and one part functional because it will throw off the entire formatting and may confuse the employer about your skill set.
Avoid being vague If you have references include them. Dont say available upon request. If you have gaps in employment explain them clearly. They will probably come up in the interview anyways. Being prepared in advance by giving complete information in your resume is better than being caught off guard in the interview or worse skipped over all together.
Combination resume is the combination of above two formats. It is getting popular these days as it includes the features of above resume formats. Just like the resume formats, there are different types of resume samples. Combination, functional and chronological are the three main types in which samples are provided on most online websites.
Mass production may be suitable for nuts and bolts; however it sure is not the right method to create your resume. This is what the resume mills or factories do - produce resumes that all look the same. When a prospective employer receives hundreds of applications and your resume is similar to the majority of them the impression created is not good enough to warrant an interview. Most likely it will not even be viewed.
The cost is too good to be true. It is only human to try to find the best service at an affordable price. However it is also true that you get what you pay for. If a service says that it can write your resume for a few dollars it is better to be cautious. Creating good quality resumes requires using specific skills. The cost can be lower only if the summary of your career is part of a mass produced set of similar documents.