I'm not sure about the BEST way - that all depends on what you have available to you - but I can tell you a bit about the different ways.
I'm assuming you're talking about the residue from the transfer paper that's left between the letters when you heat press the text so that's what I'm going to answer (I hope I got the right question!).
You can use plastisol transfers as these are screen printed onto paper which does not transfer onto the tshirt. So all that transfers onto the shirt is the design that was printed onto the paper.
You can use vinyl transfers where you use a plotter/cutter to cut around the letters for you before you heat press them, thereby eliminating anything on the area between the letters. The equipment for this isn't the cheapest thing though... it depends on where you're based.
And finally, you can just cut around the letters yourself! This is a bit time consuming of course...
Hope that helped a bit. I'm sure the experts in this excellent forum will be able to help you out more!
- Annie
Help w/Pressing Text 
