That’s OK – many native speakers don’t use this structure correctly either, especially in spoken speech, so you aren’t likely to hear consistent correct input. The subjunctive is quite useful, however – it comes in handy for making suggestions, or when you need to sound diplomatic, or quite strong, or both diplomatic and strong.
The best part is that it’s not hard to master – the construction is quite simple. You only need to learn a short list of subjunctive verbs and phrases in English and then remember that you don’t need to change the verb that follows the subjunctive verb, like this:
They suggested we try the new restaurant down the street.
I demanded that my neighbor stop letting his dog poop in my yard.
She asked that her family book the early flight for their visit.
The ‘that’ in each sentence is optional. You can say:
They suggested we try the new restaurant.
They suggested that we try the new restaurant. Both are the same.
The other type of subjunctive structure involves phrases that can be quite useful if you want to remove the agent from the sentence. For example, the following sentences convey the same message but sound quite different:
When native speakers hear phrases like #2, they think “Oh no! This is serious!” It is no longer the request of a specific person, but more like an all encompassing command from above. This can be quite useful if you manage other people and need them to really understand the urgency of a request.
For more practice with the subjunctive, we suggest you view this video from Voice of America Learning English and this tutorial with practice exercises from englishpage.com. Then put the subjunctive into practice and see if you have more success getting people to follow your suggestions and recommendations. Good luck!