These are some general tips which should be considered in mind while buying a new smartphone. First of all, you should see that which operating system you want, like IOS, Windows, Android. then you should look that what is the range which you can go for and see different brands. you should select appropriate RAM according to your usage and should select 3-4 models and then make a study among them to select the best one .you should look at your requirement which you want and select the smartphone according to it. The brand which you are selecting should have service centers in your city, this should be taken in mind.
So these are some general tips you should keep in mind to select the best smartphone for you.