It is better to use the pink part of nail clippings than the white ends because just like dead skin the white part of the nails has been changed by the body getting it ready to be discarded. For the best connection fresh live DNA should be used.

1. I have read from many UK Radionics practitioners preferring "clients" to send in a blood sample for the Witness.

But probably just as many using Hair as a Witness.

The debate is about whether DNA samples lose effectiveness through time but, I, again read that DNA is just as good years from now as fresh.
Certainly scientists extract DNA and can read it from supposed ancient plants and animals.

Here's a good youtube on radionics
Radionics interview with R Murray Denning from 1978
https://www.youtube.com/watch?v=IePLwutmWTU

and here, Danella Hester, who's machine has what looks like hundreds of Dials for settings and said "it doesn't matter how old the hair is..."
https://www.youtube.com/watch?v=nxPCnjCZb8g

2.For a sore throat we tried saliva (lasts approx ~2 days) along with finger nails; the idea being to target the bugs more directly.
I also suspect there is a difference if one is sitting next to the remote (local field and possibly audio); but this is harder to know since operator intent is also in there. 

Some grist for the mill:
My thought has been that physically the DNA acts as both a transmitter and a receiver and IS the way that communication occurs in a life-form; independent of whether that life-form is in one big piece (our body) or scattered around the place such as in the case of fungi, or bacteria. It *may* also function quite well even if we consider a body to be dead- the DNA may still communicate between themselves until the physical DNA structures get broken down. 

In the scope of a "life-time" (cell reproduction or even human-ancestory) the descendent DNA would have a stronger bond but, we could even go further and consider that most life on the planet shares very similar DNA & therefore shared communication. Its a lot like the internet LOL. The more direct the communication between transmitter and receiver; (without a lot of intermediate conversations); and, the more DNA transmitting & receiving the same message; then, the more effectively that the message gets through so as to make a lasting change.

3.In the blood is the complete information of Your body NOW status, including all parasites metals and others.
Then one point is special, fresh blood is contained in water and water is a transmitter of information. We are always in water, there is always water in the air. But it is better to use a slide and cover for microscopy, because it has the possibility, to keep the blood one week (max 7 days) in a liquid state. It is also more hygenic. Blood can be very infectious.
Don’t underestimate it, i have made many tests, it is the most powerful methology for Quantum transfer.
https://www.spooky2.com/forums/viewtopic.php?p=71269#p71269

For more details, please check the link:
https://www.spooky2.com/forums/viewtopic.php?f=9&t=8404