Everything depends on the ground
The application is a form. The outcome is decided by which ground you apply on and whether it is evidenced by documents the relevant service accepts.
The grounds differ: employment, commercial activity, family reasons, study, long-term residence through another route, and specific categories as well.
The most common mistake is choosing the ground that looks easiest instead of the one that actually matches the situation and can be proved.
Documents from abroad
This is where most of the delay happens. Every document from another country must be prepared so that it will be accepted: an apostille or consular legalisation depending on the country, and a translation in the required form. See apostille and legalisation.
Some documents have limited validity. Obtained too early, they expire while you wait for the rest. So the order in which they are gathered matters.
The deadlines people miss
The renewal application is filed before the current permit expires, not after. A missed deadline complicates the position far more than people expect.
If you are close to expiry, this is an urgent conversation.
On refusal
A refusal can be appealed and there is a deadline. Many people accept it and start again instead of challenging it. See appealing a refusal.
Bring the refusal itself. It usually shows what was considered unproven, and that determines whether an appeal makes sense or whether a fresh application with different documents is wiser.
Related
Personal number for foreigners, permanent residence, family reunification.
What I will need
Your nationality and current status. Which ground you intend to apply on. Which documents you already have and from which country. If you have applied before, everything received from the service.
This page provides general information and does not constitute legal advice on any specific case. Rights and deadlines depend on the facts and the applicable law.