Go is often followed by the preposition to when we are talking about traveling in the direction of a location. To is a preposition that gives the direction of the verb. If the preposition to were to be drawn in picture form, it would be a strait arrow connecting our current location to where we will go.
  • Tomorrow I will go to New York to see my grandmother in Brooklyn.

  • Let's go to the supermarket and get some potatoes for dinner tonight.
In both of the above examples, we are going to a place, so we can say go to.

However, one exception to this is when our destination is home, and when it is without any articles (a, the) or possessive pronouns (my, his, John's). Whether the verb is go or come or return, if home is our destination, then we do not use the preposition to.
  • I need to go to home for a few hours at lunch to meet with my realtor.

  • Rob will return to home sometime next week.
  • I need to go to his home tonight and have dinner with his family

  • Rob will return to his home sometime next week.
Another time that we say go to is when we are telling that we are going somewhere for the purpose of doing something. However, in this case to is not a preposition but is part of grammar of the verb. For example...
  • She will go to buy a new computer.

  • I won't go to see the Broadway musical.
Finally, when we are talking about going to do an activity (such as go fishing, go shopping, go skiing, go sailing, etc.) we should not use the preposition to.
  • Tonight I will go to fishing at the lake.

  • Let's go to shopping in Shibuya tonight!
If you can remember and apply these rules to your own English speaking, you will sound much more fluent. Good luck and study hard!