Hey Josh,
I fish Narra Lake a lot. Use to from the banks, then moved into a kayak and now from a tinnie with a bow mounted electric.
Pete's on the money re his suggestions. Basically anywhere where you can find intermitent weed and sand patches. Most of my fish i get in less than a metre of water hard up against the weeb beds - where the little shrimp/prawns/baitfish are.
I use to kayak around pipeclay point and most often scored flatties and some bream on small hard body lures (small attacks in pink/black my fav).
I got my biggest ever whitting off the flats on the wetern side of ocean st bridge (44cm) on peeled prawn at night. But most success on nippers, with dusk and night time the best (shallow clear water so they feel more comfortable coming up on dark).
If you can get small live pody mullet you will get into the bigger flathead. I release any over 55cm as they are mainly all females at that size. Whitebait is great though. I use a long shank 2 hook. Go thru the tail and out the eye, then do a half hitch around the tail - this secures it nicely.
One of the simplest and most fun methods i find is just taking some bread (and maybe a few frozen prawns), a few hooks and split shots down opposite the caravan park just on the corner of the weed beds at the bend. Use 4lb line, small #8 hook and small split shot a meter up the line. Chuck out a bit of bread on top and under the water. Put a little on your hook (bread or prawn) and you will get good mullet and legal bream and occasionaly whiting and blackfish. Great fun on light line and no weight.
Now it's all soft plastics for me in the tinny - around the main weed bed opposite wimbledon ave and up the back of the lake. Lot's of flathead and bream and on sunday scored a 36cm whiting on a softy.
Narra lake is probably the most underestimated bit of water in NSW i reckon. I get more legal fish out of there than anywhere. And it's the most prettiest and quiet place to fish in Sydney, especially on sunset.
Hope this helps mate.
Jake