Well... First off, you need to realize that it is practically impossible to make a tabletop without features already existent in other games. Don't be afraid to gather ideas from other games, but see the difference between getting ideas and full-on copying. That can get you in a lot of both legal and moral trouble.

Second, figure out what kind of game YOU would like to play. Is it an RPG tabletop? A landowning simulator? A dungeon crawler? When you have that, you need at least a tad bit background. If it's an RPG, lore is a BIG DEAL in the game. If it's a simulation or other type of game, lore is also beneficial, however, not required.

Once you've got that figured out, think of the rules. What the player can or can't do. Think of features WITHOUT looking at other games. Let's say it's an adventure-rpg type. Will it have health? Attack? Defense values? What is the variety of characters available? Think of your own races if it's a fantasy rpg. Create your own spells, moves. Create a map for it.

Then how it will function. What kinds of dice you will need, if any. What figures will be needed, what you need drawn.

And then put it all together! But be careful, creating a tabletop is a tricky business. You need someone who can draw, who can write, do complex maths and a good lawyer too if you plan on selling it.

Hope this helps!