Jack,
To remove tape residue, you can just use your finger rubbing over it in a circular motion, it will ball up the adhesive, then you can use a toothpick or tweezers to remove the small ball.
I would caution against using Alcohol if your paint is acrylic based, as it would be very easy to remove some paint in the process.
The trick here is not to have any residue in the 1st place. Odds are you are using regular masking tape. You need to detack the tape prior to applying it to the model surface, especially if it's been painted. You do that by sticking the tape to the back of your hand or arm. The oils from your skin will kill some of the tackiness. You need very little adhesive for masking models.
A better solution is not to use masking tape. The best tape on the market is Tamiya tape. It's rather expensive compared to run of the mill masking tape, but it's well worth it.
If I'm using large pieces of Tamiya tape, I still do the hand/arm procedure. Most likely not needed, but I'm so use to doing it, it's 2nd nature to me.
Joel