How to do a Basic Wire Splice
If you want to get anal like I do - cut / splice / solder / ohm check / then heat shrink....
In most projects I ohm check across the splice to verify a good splice and that there is not a huge ohm build up... I also instead of using the twist together method I use a non-insulated butt connector and crimp that / solder it.... drastic overkill? yes.. but I am just like that when it comes to electrical...