Please note that at most consulates and embassies consular services often are not not accessible on a walk-in basis. In most cases you need to make an appointment first.
You can check on the official embassy/consulate website how to make an appointment. You can also call them first or send them an email.
Embassies always offer the widest range of consular services. Many smaller consulates do not offer consular services at all and only offer limited services.
Important: always check up front what specifiic services are offered and if you need an appointment.
Automated appointment systems
Most embassies and some of the bigger consulates nowadays have automated appointment systems which can be accessed throught their official websites.
Most smaller consulates will automatically redirect you to such an online appointment system and most consuls require that you make an appointment by email or phone.
Many smaller consulates around the world are the smaller honorary consuls. These consuls often do not issue visas or passports.
For visa and passport related matters you better contact a bigger consulate general or the embassy of your home country.
As you notice it is important to contact your consulate or embassy directly before you need any of their services so you know if the consulate offers specific services you need and if you have to make an appointment beforehand.
For information on appointment, inquire the consulate or embassy of your home-country directly by email, website or telephone call.