Most practice exercises that I’ve seen are fill-in-the-blanks, multiple choice, matching, and similar forms. The purpose of these is to have the students use the featured grammar structure over and over again, and perhaps with different variations, until they can use that structure when prompted without much difficulty.
The problem with these exercises is that students already know which structure they should use. Maybe they need to figure out which usage to apply it to, or maybe they need to select from multiple variations of that structure, but still, the starting place in practice better matches the conclusion in free production. In natural production, learners should first determine the purpose, meaning, or usage, and the structure would then be selected as a result.
It’s a cart-before-the-horse situation.
Think of it this way: Suppose a student has recently learned the 1st Conditional and has practiced it well. Now she’s ready to use it in the real world. But when she’s having her next conversation in English, she’s not going to stop and think, “I should find a reason to use the 1st Conditional. What can I say that would make use of that form?” No, first she decides what to communicate, and next comes her decision on how to communicate it. But in practice, we start with how to communicate (the topic of the lesson) and come up what to communicate just so we can use that topic.
Don’t get me wrong: those practice forms do have value, and I’m glad we use them. However, there should be more steps that follow if a student is to master that grammar structure.
If there was an outstanding solution to this, I’m sure teachers would already be using it. The best option I can think of is to practice multiple grammar structures (likely reviewing past topics) without letting students know which they should use. Given particular applications, students would then be tasked with figuring out the best structure for each.
Maybe one day I’ll draw up some example lesson plans for how this works, but at the moment I haven’t worked out the specifics. It could be done with the occasional session-long review, or could be a five-minute activity you do each week. Giving the students a scenario and asking them how they would respond is probably the way to go (where you’ve chosen a scenario that lends itself to one or two of the grammar structures the class has learned in the past month).
You might have your own ideas on practice or production activities, or you could find plenty of ready-made others that will suit this purpose. But be sure to engage the students in this way. However you do it, after the students practice how to use a grammar topic, find a way for them to learn when to use it.