Begin with the problem you are solving, not your preferred technology. What kind of user will use it day to day, with what frequency, and what does the process look like without it? An experienced team who knows what you are trying to achieve can propose an alternative that costs less; one who only sees a feature list will price exactly what you asked for.
Describe the scope as concrete flows: what the user does and dedicated teams vs project-based outsourcing what the system does hire developers in russia response. Equally important, state explicitly what the first release deliberately excludes. A written out-of-scope list saves more argument during acceptance than any other single page. Mark too which decisions are settled and which may still change — estimators price uncertainty, and hiding it helps nobody.
List the constraints. This means systems you must integrate with, the data you have and where it lives, compliance requirements, user volumes, which devices matter and infrastructure that is already decided. Where a date is genuinely fixed, retail ecommerce software development company say what depends on it: a good team can often cut the right scope to hit it, but not if the date is a secret.
Write down what the word done means for the important items. Acceptance criteria need not use special syntax: a plain-language note describing what a user should be able to do is sufficient. That one addition compresses the review at the end considerably and eliminates the most common source of disputes.
To close, say what you expect back. Ask for a breakdown by feature or module, the assumptions used, the main risks and an optimistic and a pessimistic figure. Take a broad range as a signal about the brief: it normally identifies the part of the brief that needs work. Then clarify that area and ask again — the second estimate will be far closer to reality.