Crayola coloured pencils seem far better than the Faber-Castell efforts at the lower end of the market.
Stabilo erasers are great, and you’ll need a decent pencil sharpener.
I like to add some highlights with paper mate inkjoy gel pens.
You could also try using fountain pens. Amazon are selling 8 jinhao fountain pens for about a tenner.
If the paper is decent quality, you might get away with using highlighter pens on some parts.
I’d avoid using felt-tip pens as these can bleed through. Though, when they’re about to dry out, they can add some interesting effects.
Cheers😉