Start by cutting the paneer into cubes or 1/2" slabs (cubes for curry or skewers, slabs for grill or bbq).
In a bowl, mix the oil, lemon juice, garlic, garam masala, turmeric, cayenne powder and salt.
Add the paneer cubes to the bowl. Gently toss them with the marinade, making sure each piece is well coated. Be careful not to break the paneer. I find it easiest to use my hands.
Let the paneer marinate. Even 15-30 minutes can make a difference, but if you have time, letting it sit for an hour or two in the fridge will deepen the flavors.
After marinating, you can cook the paneer as desired. It's great grilled, pan-fried, or added directly to your paneer curries for that extra layer of flavor.
Notes
If using marinated paneer in recipes (which I recommend - it's so good!), reduce the amount of salt and cayenne (or kashmiri chilli powder) in the curry by 1/2 tsp to account for the salt and cayenne added directly to the paneer.
Then, taste a spoonful of the curry with a bite of paneer before you decide if you should add more salt or cayenne/chilli powder to the sauce.