Bluffs Gone Wrong

So I've been noticing a weakness in my game. I will make stupid bluff attempts at medium-small size pots that my opponent calls with middle pair or low pair. So I asked myself, why does my opponent know that I'm bluffing?

And its simple really, I am not making my hand believable to my opponent. Here is an example of a situation:

I raise in EP with AK, one caller.
Flop: J 9 5

I c-bet 4x BB
Villian Calls

Turn Q

Villian Checks
I check right behind him

River: 7

Villian Checks
I make a bet that resembles a value bet
Villian Calls and shows 10,9

What went wrong here? I made a dumb attempt at the river to win the pot. I heard somewhere recently that when you bluff, you should know exactly what you are going to do PF and you need to put together a puzzle.

If you just throw some pieces in at the last minute, the puzzle will not look good. So now, I no longer make unwarranted bluff attempts at the river. If I bluff, I will set it up PF, and commit to it post flop. I find that now my bluffs are much more believable, and I am seeing many more folds at the turn and river.

Let me know what you think.

In the hand, you are raising preflop, so the guy think you got Ax or KX, or pocket pair, or nothing, in the flop is no A or K, so the guy pay with 9's.

In the turn comes Q, now he got not only 9's, but also have a 2 ways straight draw (9,10,j,Q), so he check expecting to know where he was, but you check and give him a free card, and also make him feel you got nothing

if you raise in here maybe he trow the hand, or at least think that you got a hand, but because you check in the turn, he think that you dont have nothing.

In the river dont hit the straight, but a 7 come, so he think your hand is not better than before, so, he is going to pay.

Bluff is part of the game, but as you said have to be believable, and if you going to bluff, make it strong.

And bluffing or not, never give freecards in the turn.

I also think a bet on the turn, and than river would have worked also. After he didn't hit a straight on the river, I could have moved him off the hand after betting on every street.