Semi-bluff or take free card?

[jskinn04]

My opponent seemed like a fairly liberal caller, but I had not bet very during the heads up session in an attempt to catch a big hand and trap her. I picked up the four-flush on the turn and I decided to semi-bluff; however, I only made the minimum bet. Against this type of opponent, should I have just checked and taken my free draw, should I have bet a larger amount, or should I have done what I did. Another reason that I bet was to protect my hand in case I had the best hand. Does that make any sense?

NL Texas Hold'em 10 Buy-in + 1 Entry Fee Trny:15139814 Level:8 Blinds(200/400) - Thursday, July 28, 15:54:52 EDT 2005
Table Play money 4008853
Seat 4 is the button
Total number of players : 2
Seat 6: jskinn04 ( $3890 )
Seat 4: juanita_mm ( $4110 )
Trny:15139814 Level:8
Blinds(200/400)
** Dealing down cards **
Dealt to jskinn04 [ 2s As ]
juanita_mm calls [200].
jskinn04 checks.
** Dealing Flop ** [ 9s, Tc, 4c ]
jskinn04 checks.
juanita_mm checks.
** Dealing Turn ** [ 4s ]
jskinn04 bets [400].
juanita_mm calls [400].
** Dealing River ** [ 5c ]
jskinn04 checks.
juanita_mm checks.
jskinn04 shows [ 2s, As ] a pair of fours.
juanita_mm shows [ Qh, 9h ] two pairs, nines and fours.
juanita_mm wins 1600 chips from the main pot with two pairs, nines and fours.

[amoeba]

I think turn bet is fine and best line here.

if you check, you have no idea whether he is betting based on weakness or whether he has paired up.

you might also consider crossposting in hu forum.