If your food is constantly over or undercooked try closing the lid.
Keeping it open allows the heat to escape and compromises the roasting. Use high heat to sear thick cuts of meat then lower it to finish.
If those fatty foods are making the flames flare up -- spread things out.
Keep a third or more of the surface empty.
This way if when the flames start to kick you can move your food to the cooler, non-flaming section.
And if you've got more food left on your grates than your plates think about your heat.
Fully preheat the grill for about 15 to 20 minutes.
Clean those grates with a proper brush, then fold two paper towels into a tight pad, dip it in vegetable oil and wipe it across the grates using tongs.
Now you're cooking with gas -- or charcoal