1. The best thing is you should be specific in things that will you search. Like in Microsoft what do you want to search about them? For an example you want technical support from them you can search for Google "Microsoft support". And the support website will appear.
2. You can also use the custom search of Google. For more websites and specific webpages you want to search.
I hope this suggestions will help you. And have a nice day!
You can found specific website on Google just putting full website name, here you must be so careful about spelling of website name. The keyword that you use to search a specific website it should be very specific for that website. Adding extension is important to search a specific things in Google. Adding extension means .com, .org, .net and for looking pdf document .pdf .