I use a non-contact tester from Screwfix, which I find very satisfactory.
https://www.screwfix.com/p/lap-ms890...E&gclsrc=aw.ds
When you switch it on the tip glows green to show that it's working, then if you touch the insulated tip on say the screws on a light switch fascia or 13A socket outlet, it will glow red and give an audible warning to show that it's working correctly and the circuit is live. A much better indication than a neon tester which often glow only dimly. With a neon tester our body is of course part of the circuit so the better we are grounded, the more conductive well will be and the brighter the neon will glow. With the neon on a live contact and your other hand on say a copper water pipe, the neon will glow very brightly indeed, but remember that our heart is in the middle, so ventricular fibrillation may arise.
I binned my neon long ago; too young to die - too old for nasty shocks.
'It's Volts that jolts and mills that kills'.