Not sure if I could come up with anything too good myself, but I can describe a few things I like and don't like in board games:
Make sure the game is as little luck based as possible. It's always funny to see someone get screwed over, but nothing is lamer than a game where winning or losing depends (almost) entirely on how well you role the dice. You might as well go flip coins.
Games that require strategic planning and thinking are usually much better. They tend to be a lot more immersive, more challenging and it gives players a lot of satisfaction to see their plan going well (which adds to the fun). Don't make the game too complex though. If you need to add a 50 page manual just to explain everything people might get turned off before they even start.
Make sure the game isn't too long and make sure everyone at the table gets involved enough. I've played some games that took more than 3 hours and where you get your turn like once every 20 minutes. It won't take long before people get bored and start walking away to do other things. One hour tends to be about as long as people would like to play and consider adding a trading phase after every turn or something (if people's turns may take long).
Preferably make it playable for 2 to 6 players or something. It's always a bit annoying if a game requires exactly four people because often you're not with four people. Even if you are, there's often someone who'd rather play something else or doesn't really feel like playing and that just sucks.
Lastly, I would suggest you just go out and play/look at as many different board games as you can just to gather ideas.