made a mistake preflop ,an i m left scratching my head.

[frenchfish]

Poker Stars - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 6 Players - (LegoPoker Hand History Converter)

Hero (SB): $337.30
BB: $59.80
UTG: $115.35
vilain (MP): $60.00
CO: $106.55
BTN: $149.90

Reads: <font color="blue">no reads</font>

Preflop: Hero is dealt A[img]/images/graemlins/heart.gif[/img] J[img]/images/graemlins/diamond.gif[/img] (6 Players)
UTG calls $1.00, vilain checks, 2 folds, Hero calls $0.50, BB checks

Flop: ($4) J[img]/images/graemlins/spade.gif[/img] 4[img]/images/graemlins/heart.gif[/img] 6[img]/images/graemlins/heart.gif[/img] (4 Players)
<font color="red">Hero bets $2.50</font>, 2 folds, <font color="red">vilain raises to $10.00</font>, Hero calls $7.50

Turn: ($24) 3[img]/images/graemlins/heart.gif[/img] (2 Players)
Hero checks, <font color="red">vilain bets $20.00</font>, [i]Hero ???

I m rraising preflop 99.99% of the time here but i was involve in a big hand on other table and just called [img]/images/graemlins/frown.gif[/img].
How is my line and what should i do on the turn.