Teach Aspects instead of Tense Combinations
It's all too easy for students to confuse one tense with another. Twelve tenses (depending on how you count them) is a lot to keep track of when each has its own rules for form and usage. I imagine by the time they learn the sixth tense, some of the students are already thinking, "What? Another one? How many of these do we have to learn?" Then remembering the difference between one tense and another can be tricky if it's been a while since you studied one of them. And even when they remember how and why to use a given tense, they might forget what it was called, so asking them to recall the rules of a tense might result in blank stares.
How about this: instead of teaching each tense separately, teach aspects. Once students are clear on the differences between past, present, and future, teach the continuous aspect, then teach the perfect aspect. After that, each time students need to determine a tense, they only have to ask three questions:
Is the focus on the past, present, or future?
Is it perfect or not?
Is it continuous/progressive or not?
(with the understanding that the 2nd and 3rd questions should be asked independently of one another; the answer to one should not affect the answer to another)
Now, I'm an analytical person; I like to break things down into different components, then see how they can fit together again. In my mind, I build a verb string from scratch instead of choosing one of the predefined tenses and plugging in the main verb. However, I recognize that not everyone thinks this way. You can't really just teach the aspects to elementary or pre-intermediate students, then step back and expect them to form all twelve tenses without much difficulty.
But what you can do is draw attention to the aspects as you learn a tense. For example, what make a present continuous verb, well, continuous?* Downplay the present feature (once students have grasped that) and ask what the difference is between continuous and non-continuous (simple). (This is why it's great that some books have units just form comparing two similar tenses.) Have that be the big take-away. Later, when study past continuous, review what it means to be continuous. Then take a past simple verb and make it continuous. Or take a present continuous verb and make it past. Making adjustments to what students can already do is less daunting than approaching a new tense from scratch.
Do the same with the perfect aspect* when you teach present perfect. Once they understand how present perfect works, it's a very small step to use past perfect (or future perfect, for that matter, although it's less frequent).
Then imagine teaching the present perfect continuous tense. It's considered a more advanced topic, but at an early intermediate level, learners should already be familiar with present, with perfect, and with continuous. Simply put them together (we'll do a video on this later) instead of considering the tense as something entirely new.
It's like non-overlapping descriptors of almost anything. Consider a building for instance. Is it residential, commercial, or public? Is it large or small? Does it have a modern design or a more traditional one? Once you understand each of these three factors, you don't need to explore every combination. If you see a large modern residential building for the first time, you're not confused by it, and you don't need to spend a lot of time understanding it. You know what it is because you've seen large traditional residential buildings and large modern commercial buildings in the past.
Anyway, I'm not suggesting you do a unit on the perfect aspect independent from tense. I'm just saying that when you study a perfect tense, connect it with other perfect tenses you studied in the past, and generalize the perfect aspect enough to connect it with more perfect tenses you'll study later. Same with continuous.
When you take a step back from the specifics so that students can see the pattern, they can more easily comprehend the next tenses you present, and they're more likely to remember one tense from another.
* Continuous (or progressive) tells us that the verb is ongoing or that it is active in the moment. Perfect tells us how a verb started earlier affects the situation of the moment.