I've got chicken thighs marinading in the fridge...

[snickersnack]

...how do I cook them? I've grilled them before but they dry out. I'm sure my dad does something on the hob first then sticks them in the oven - any thoughts on methods and timings?

I would just put them in the oven, approx 180 fan (200 conv oven) for 30 mins.

Recoat with marinade about half way through.

You could brown them on the hob, then add a cup or so of marinade, bring to a boil, then reduce to a simmer for twenty minutes, turning halfway through.