For one Tv connected use no splitter.
For 2 Tv's connected I recommend a
http://www.hollandelectronics.com
HFS-2D 2 way splitter.
At solidsignal the HFS-2D is $2.99 , very low price for such a High Quality splitter.
However if you have a 2 way splitter then use what you have.
A common 2 way splitter will work Ok.