Hand bothering me from afternoon 320 on stars

[ZJ123]

I have 3k to start hand blinds are 50/100

In LP i pick A [img]/images/graemlins/heart.gif[/img] T [img]/images/graemlins/heart.gif[/img]

Folded to me, i make it 300

Only BB calls, read on villain is he is a pretty good TAG that i recognize. Though im not completely familiar with him. His Stack is a little over 4k.

Flop is K [img]/images/graemlins/heart.gif[/img] J [img]/images/graemlins/spade.gif[/img] 6 [img]/images/graemlins/heart.gif[/img]

He checks

How much do you bet and why?

or do you check?