When using a crock pot do you just place raw meat and veggies all together n let it cook, or must you cook the neat first?

Cataluna, I assume you mean you brown your meat first, not cook it? It doesn't need to be cooked through before adding to the crockpot. If you're concerned about food safety, you can start the pot on high for up to an hour before reducing the heat to low. This gets the food up to a safe temperature faster.

Soft Punk is right, i always cook my meat first for flavor. But if you're in a hurry you can add the veggies without browning them at all, and the crock pot will cook everything to a safe temperature for eating. So from a food safety standpoint you have nothing to fear by adding raw veggies and meat. but from a food flavor standpoint you should definitely brown you meat and preferably veggies first.

Browning the meat first will provide much better flavour. After browing the meat I would deglaze and add the juices, or use the rendered fat to quickly sauté onions, etc. the recipe calls for. Yes, it's an extra step, but you will have a far tastier dish as a result. And definitely, add fast cooking veg and green herbs you want to stay green toward the end of cooking.

I would recommend browing the meat on the stove and then adding it all in for better texture & taste.

I add it all in together might want to add some of the shorter cooking time vegs towards the end.