I use Tamiyas clears and always brush apply. Never had a problem with them pooling round the edges.
When the kit supplies a clear lens I apply bare metal foil to the part it attaches to, then glue the clear part to it with Krystal Kleer, then brush paint the outer face of the clear lens. This is an example;-
For 'solid' lights, ie made of non transparent plastic, I apply Bare Metal foil, coat with Johnsons Klear, then apply the clear paint to that. The indicators on the M113 are done that way;-