Doing the paperwork for a visa can be error prone and a lot of work. There is, however, a better way. Or at least a way which provides a better chance of a result. There are businesses called visa services. For a fee (of course), they will shepherd your visa application through the bureaucratic maze.
Visa services do not have any ability to get a visa approved that would otherwise be denied, or to bend the rules in any way. They do, however, work with the various embassy visa departments’ personnel on a regular basis, and they are familiar with all of the ins and outs and gotchas. Visa requirements often change and are sometimes vague or subject to interpretation. Visa services actually understand what the consulate personnel require (as opposed to what their instructions imply).
WARNING: Any visa service that offers any kind of guarantee is likely a scam. Visa services have no secret powers and your application will succeed or fail on its own paperwork merits. Visa services’ “value add” is their familiarity with the process, their traceability, and their focused physical presence. They hand-carry paperwork, expediting its physical passage, and can often get visas quicker than would otherwise be typical through the mail.
The visa service will check your application at the start of the process to ensure that all the required paperwork is correct. Often any issues can be caught early and corrected with a fax. Then they will hand-carry the paperwork to the correct offices. They will check back at the appropriate times, and provide traceability on the entire process. In the event of any kind of issue, they will do the legwork to run it down and correct it if possible. Lastly, they will overnight that precious passport and visa back to you by reliable courier.
Visas applied for through visa services tend to have less drama and be issued on the expected timeline. Professional visa services facilitate matters for everyone concerned.
One reputable visa service is Travel Document Services (TDS, or just “TravelDocs”). I have used them on numerous occasions and been well-satisfied.