The Russian language has six cases to show what function a noun has in a sentence: nominative, genitive, dative, accusative, instrumental, and prepositional.
1 Tip—Don’t be afraid to make mistakes
This tip doesn’t apply to you if you prepare for the TRKI exam.
Russian cases are not as important as tenses, for example. Everyone can understand you even if you mix the endings. If your goal is just to speak, you don't need to learn all these endings and memorize tons of tables. All you need is to learn personal pronunciation in all the cases because it might be confusing if you don't know how to use them.
2 Tip—Don’t learn all the cases at once
It might sound obvious to you, but you can learn the cases one by one thinking that you are already professional at it and going to practice the next case. However, it is better to dedicate enough time to practice one case. Duolingo really helps with making a habit. However, it is much better when you have a Russian tutor who can assign you exact lessons, so you don’t waste your time learning obvious things.
3 Tip—Learn cases in the exact order
Learn cases in this order: genitive, accusative, instrumental, dative, and prepositional.
Order is very important because this way you can start speaking much faster. Genetive and accusative are the most often used cases, so it is better to learn this beforehand.