keep your weapon upgraded, switch targets with your threat combo, use flash A LOT as it does not interrupt your combos and really pay attention to what targets your dps are hitting

this is key to keeping threat as a paladin at low level

like yeah you can buy gear and it will help some but not more than your weapon and paying attention

I will usually open with a shield lob and use flash 4 or 5 times before even starting threat combo when i played paladin and that's always worked well