I often find myself having issues while researching different parts of history. I’ll either be researching something about the two world wars and not find enough information on a specific topic, or I will be researching something like a Vikings or ancient Greeks and never be able to find anything about a specific scenario just for example. So could somebody tell me a good way or perhaps a good website to go to to make this a better experience for me?
Leaving aside professional or academic research which has its own expectations, historical research for your own edification often comes down to digging a bit further into the book you have just read, specifically into its references and bibliography.
Most reasonably good history books will have references in them - usually footnotes or endnotes where there is a number in-text which takes you to a reference for that information either at the bottom of the page, or at the end of the chapter. This will show the reader where such information is drawn from. For example if the author in a general history of a war references details from a particular battle, then you might expect to find a reference to a work specifically about that battle.
If they don't, or it's a more popular history book (which understandably forgoe references), then always check the back of the book where, if worth their salt (or the editor allowed), the author will have included a long list of works they used in the writing of the book. In this list should be many more detailed histories of the period that the author has read and which you might then find useful.
Failing that, an Internet search of the book you have just read, and looking for connected literature might help.
But don't be too hard on yourself, sometimes no one may have written anything substantial on the niche piece of information you want more detail on.