Since you've gotten this far, I'm going to assume you know how to use resistors to modify the sensor signals, so I won't go into those details unless someone asks.
The first sensor you want to tune is your CTS/CHT sensor. You have to find at what temp your electric fan kicks in, and if you don't have an electric fan, at what temp does your ECU go into internal cooling mode (your Hyundai has an electric fan so you won't really have to worry about internal cooling mode for the most part). If, for instance, your electric fan kicks in at 225°F you want to keep your temperature below that temperature. In my '99 F150 I set my CHT to 220°F once everything is fully warmed up. 215°F to 230°F is the range you want to set it. You should note that offsetting the CTS/CHT sensors could cause cold start problems. You'll probably want to add a switch in-line with your resistor so you can shut it off until the engine gets warm enough to run with the offset. Many people use a thermal switch that closes once it gets to a certain temp.
The IAT is the next sensor you'll want to address. Typically you want it in the range of 130°F to 150°F range on the hottest day of the year. **NOTE** The IAT is one of the ECU's two main determining sensors that control ignition timing, the other being your MAF. You will have to make performance tests to determine the perfect temperature offset for your IAT. The IAT generally won't cause cold start problems.
Most vehicles generally don't have AFR's and O2's together; I'm not exactly sure which your vehicle has (they work differently). The O2 sensor signal can be modified using an EFIE or similar device (I think someone on the forum has built a new-and-improved version of the EFIE). IIRC, I believe the original EFIE had a design flaw that would burn out the transformers. The oxygen sensors generally only have control over the mixture at medium to light loads and cruise, and therefore you don't have to worry about damaging your engine by setting the O2's leaner.
Get out on the highway and cruise along, using no more than 1/4 throttle. Lightly feather the throttle to get a feel for your current throttle response and performance (1/4 throttle or less). Once you have your baseline, you can start modifying the O2 sensor signal. Make a small adjustment and compare your before/after performance. Once your throttle response starts to get soggy and performance drops, go back to your next best setting. **NOTE** A loss in throttle response and/or power denotes a loss in combustion efficiency. If your engine is running worse than before and you lose any noticeable power, you've gone too far.
There are different types of MAF sensors as outlined in the tuning article; I don't know exactly which one your vehicle has so I can't give you any specific guidance. However, I was able to add resistance to the signal wire of my MAF to offset it a bit. **NOTE** The MAF and MAP sensors are your load sensors. Offsetting these two sensors too far can easily cause damage to your engine. You tune these sensors the same as your O2's, except your romp on it instead of 1/4 throttle or less and you want to start at slightly richer than stock. **DOUBLE NOTE** Do not hold it at WOT for very long. You only want to be able to detect a performance drop. Staying under load too long while running too lean can melt pistons, valves, etc.
Once you feel a performance decrease, go back TWO OR THREE previous settings. This is for safety and longevity; getting great mileage doesn't help any if you have to buy a new car/engine a month down the road.
On my '99 F150 I added a 200k ohm resistor on the MAF signal wire. Note that Ford and Mazda uses high-impedance sensors. Where I need 15 or 20 k-ohms across my sensors, you'll probably need closer to 5k.
I've probably forgotten something; I'm at work right now and am distracted.
Ask more questions and I'll try to answer the specifics as much as I can.
Here's a picture of my current heat exchanger.
I don't know exactly what temp the fuel is coming out of it, but it's hot enough that I don't want to touch it for very long.
The red tube also has a bunch of magnets in it, so it's a fuel heater and ionizer. It came with the HAFC kit, though the PCV pipe surrounding it is my design; they recommend simply wrapping the red aluminum exchanger with a heater hose.