Do you worry about what is going on outside your door?

Many of us do. We care about our neighbors and want to have a harmonic living environment. However, some times there might be a small road pointing at the front door at a not-so-welcomed angle or the house across the street just put up a pointing mailbox. Maybe not exactly pointing at the front door but it just does not look very friendly. What about living in an apartment building and your door is just a little too close to the elevator (or stairs) than you wished? Little stuff like this maybe not bad enough for us to make a big deal about it but it makes us somewhat uncomfortable. 
This little discomfort, which is a little disharmony, can add up and become costly. In Chinese new year you can find many nice red door decorations in China town or your Asian food store. A red decoration on your front door could provide a good help for your Fengshui. For as little as one dollar (or less), you can find Chinese (new-year related) character on a red paper. There are also many nice decors available in most of the stores.
If you want to spend a little more time on it, you can also get some nice welcome door decoration from your local art and craft store. Make sure the decor goes well with the door and the environment.
Don't use things like Ba-Gua mirror unless you are instructed to do so by a practitioner after on site consulting.  Mirror is too obvious and can be offensive..