Every card is different. A MSI 290 will hash different than a Sapphire 290. You need to find your settings that work well for your cards/system.
On top of that, each GPU will have it's own limits. Some cards OC better than others. Some will hash better than others. It's all a huge mess.
There are some known starting points for you to work off of. Example is the TC. A lot of people use TC 32765. Try what other people are using, and see what other people's setting get you.
If you're not happy with that, check out these two blog posts. They contain a set of scripts that you place inside your SGMiner folder, and run them with some set parameters. It cycles through, running a 5 min test with each setting, and then records the hashrate. Helps you see exactly where your cards peak, and where they fall off. You can use these to see exactly what setting will make a difference on your hashrate.
http://www.holynerdvana.com/2013/12/cgminer-optimal-thread-concurrency-for.htmlhttp://www.holynerdvana.com/2013/12/finding-optimal-clock-speed-for-cgminer.htmlI would start with the TC one, and set a middle-of-the-road core/mem settings, say 1000/1250. Run the full TC test, and see what it says your best TC is. Then run the mem test, with a core of 1000 and your best TC. See how high your memory goes. I can only guess, but I'm gonna say your mem probably runs best at 1250 or 1500, due to timing issues. Then, run the core test, starting really low and working up, to see how high your core should be.
You will have to edit the script files, esp when how it runs sgminer (it will try to run cgminer). Include your pool info, as well as known optimal settings, such as -I (or -xI), -g, -w, -k, and --gpu-fan settings.