Quick Answer: You'll definitely want to press tofu before marinating. This is especially true if your marinade has any sort of oil in it. Any water in the tofu will prevent the oil from the marinade from seeping in because water and oil don't mix!
If you are thinking about marinating tofu, here are a few other additional tips and answers that you'll find helpful...
Use a Press
Using a tofu press will really help the process of water removal be quicker and easier. They are devices designed specifically to get the water out of tofu without the fuss or mess of doing it manually.
You can certainly do it without one, but I've always found it to be a huge pain. Since they only cost around $20-$30, I've found mine to be a very worthwhile investment. You can even plop the tofu right into the refrigerator while it's pressing all day. This way when you get home from work, it's ready to go!
Check the link above to see which ones are my favorite.
Dusting or coating the outside of your tofu after it's marinated will help it get that extra crisp that you've probably only had in restaurants. This is true even if you don't fry it. It will even help it get crispier in the oven!
All you need to do is have the outside of the tofu be a little moist with the marinade. Then just roll it around in some cornstarch or sprinkle it on top to get a nice crunch.
You Don't Need Long
If your tofu is pressed and dried and you've gotten the water out, you really don't need it so sit that long in the marinade. After all, it's pretty porous and is going to quickly absorb whatever is surrounding it.
You can marinate tofu overnight, but usually it will reach near maximum flavor capacity in around 30 minutes if all the water is out. Obviously the longer you leave it, the more the flavors will absorb and develop. But for a decently flavored marinade, most people aren't going to notice a huge difference if you leave it for longer.
Try Different Cuisines
Many people think that tofu is limited to Asian cuisine, but this is simply not the case. You can literally season tofu any way you like and it will still taste good. Think Italian, Mexican, Ethiopian-style.
Seriously, you name it.
You can also use tofu in sweet applications like puddings and other desserts. Don't be afraid to explore all the options.
Try Different Shapes
You don't only have to eat tofu in blocks or slices. Did you know that you can crumble it and make it into something similar to eggs? That's right, it's called a tofu scramble and it's delicious!
If you throw a little bit of turmeric on it, it will even be yellow-colored! Throw a little bit of nutritional yeast for umami and black salt for the "eggy" sulfur flavor.