English is easier than some languages, but harder than others, in respect to tenses. In English, we don't make too many changes to our words to show that we're changing tense. e.g. I walk, I walked, I will walk, I was walking. We have some irregular verbs (I write/I wrote), but some languages make many more changes. Perhaps you speak one of those languages? Conversely, other languages don't change their verbs at all, and all the work is done elsewhere in the sentence, by another word that indicates whether you're talking about the present, past or future.
One thing I'm often asked by students writing essays in English, then, is what tense they should use. The answer depends very much on the discipline for which you're writing, but in general you can use the present tense when you're talking about ideas (e.g. Smith claims that . . .) or general truths (e.g. Water boils at 100 degrees centigrade) and the past tense if you're talking about past actions (e.g. The researchers surveyed 300 people). The funny thing about academic writing in many disciplines is that you can use the present tense even when something was written a long time ago (e.g. Shakespeare says . . .; Brown (1962) notes . . . ). If you're talking about an experiment you propose to do, though, you should use the simple future tense: 'This experiment will investigate . . . It will use . . . ' When in doubt, check with your department for any particular conventions you should follow.
One tense that seems to be vanishing in Australia is the past perfect, used in what is often called the 'third conditional'. e.g. 'If I had known you were coming, I'd have baked a cake.' I often hear people now saying, 'If I knew you were coming, I'd have baked a cake.' (Actually, no, they don't bake cakes for me, but they could do!) I know what they mean, but I like the past perfect here. What do you normally use? I've put a poll up so you can give me your votes on this.
Whatever your views, there's no doubt that language changes, is always changing and will continue to change!