We could have scientists and other experts pontificate for the next 100 years, and they still couldn't come up with any way to better guard from future outbreaks, because save locking up every single person in total isolation for weeks or months on end future viruses will spread. That's how it has been for hundreds of millions of years, and its about time we came to accept this. In fact even total isolation, and by which I mean zero human interactions, would not stop viruses, they simply jump species when one host becomes unavailable. This is one of the problems that has emerged from this pandemic, what someone else on these forums described as "human exceptionalism". That is to say that some people have formed the opinion that humans must be able to survive absolutely anything, and that mortality should no longer be a fact of life.
Now that's not to say there are not things we could do to mitigate some of the problems. For a start governments around the world need to not only better invest in health services to ensure that not only is there capacity for usual times, but there is built in excess to deal with future pandemics. Furthermore governments need to work better together to share capacity, share knowledge and resources. The same can be said for pharmaceutical research, development and production. Instead of different countries all engaging in was little more than a restriction & vaccine peeing contest, they need to better work together to develop vaccines & treatments that can be rolled out quickly and effectively to all countries, not just those that can afford them. This will help mitigate those early stages where viruses quickly mutate and rip through poorer, less exposed to vaccines countries.
But most importantly, and currently most ignored is health. The healthier a population is, the less likely a future pandemic will be so disruptive. And again this requires global cooperation to get the globe's people better access to healthy food, to medicines, vitamins, treatments and quality of life. Instead of trying to micromanage each virus as they appear, we should be looking to ensure more people have access to what they need to be healthy & have healthy immune systems. That is how you best manage future pandemics, incredibly difficult I grant you, but it is the best way & far more preferable than locking up entire countries or locking down our little lines in the sand.