There are no rules dear @Fatimah! I do start with previous results and papers published in the research study area, as @Mahfuz stated, then I write about the scope/objective of research and give a short abstract on paper with possible application of results!
I think it is important to try to relate the content of the article to your everyday life. That way, someone who reads it is less likely to get bored and stop reading halfway through. First impressions are very important!
I know that this is much easier said than done, however. The introduction is often the most difficult part of the paper to write, so it should be saved for the end of the study (like the abstract) when you (ideally) know all there is to know about your topic.
Maybe the question was not directed at me, but I must say that if you write your abstract first, you risk writing it wrong. No matter how sure of yourself you may be at one point, remember that experience is still more valuable than raw knowledge. The scientific writing process never ends.
I just start writing with a rough overall sketch, then give to my colleagues for some filling works, finally I add again, make improvements, check, edit and if needed again take help of my junior colleagues - then a final check and submission; like filling muscles and blood in a skeleton
What is the best introduction to an article to be submitted to an A-ranked journal? In my practice I write 1 to 2 sentences why I'm writing the article then followed by description of the main topic that I want to introduce.