Welcome to the sport. I started in IK's in the early 90's. For paddles, I like the basic Carlisle take aparts, but not the RS ones. They break. The cheap ones that look like raft paddles will last forever. If you want a real kayaker paddle, buy a real single piece Werner/ Lightning/ Sawyer paddle. The mid level paddles seem to break.
Buy a good vest, that is intended for WW use. Look at sites like NRS, Cascade Outfitters, Down river equipment, The Boat people, Clavey, Man of Rubber, or some of the the vendors I haven't mentioned on this site. Fit a helmet you like to wear, I'm not too brand Specific. It just needs to be intended for WW use.
Footwear is pretty important to me. I have big feet (16EEE) and I don't like them to get injured, so I wear Booties from NRS that protect them, even when it's hot. Saves my toes when I take a spill.
I have no clue what you level of comfort is in water, but I recommend practicing self rescue with your craft before you really need to. Flip it, don't touch the river floor, right it, and re-enter. Make sure you you can quickly. Make sure you hang on to your paddle when you swim.
The most important ingredient on any trip are good people to boat with. I like to have people better than I am on every trip, so I learn and grow, and I love to help out the people who desire some help. The people you boat with are like comrades in war, so that is the level of trust they will expect from you and you should expect from them. I put more thought and care into who I boat with than what I paddle