Jodes have found these type of crimps - this will be fine around £25-30 , I have had mine for years .
Insulated Terminal Crimping Tool - Standard Duty | 12 Volt Planet
Not that you will need all of these but this type of crimps.
385 Piece Pre-Insulated Terminal Kit | 12 Volt Planet.
depending on how many wires are going in , the red should be fine for 12v.
The jaws on crimper are colour coded so you cannot go wrong- I find it easier to put crimp in jaws first,
Crimp down so it just grabs it , then inserted stripped wire with other hand and just crimp down- it will not open up until you have right pressure - so cannot get it wrong mate- just practice on a couple first.