Make sure you have tix. If not try Stubhub. You can walk up and pay entrance fee for just the carnival and livestock show; carnival rides cost extra as of course food unless you have chute seats, action seats, or entry into a suite.
Try to go early on a weekday if you want to see the livestock show and/or the carnival (those open ~11 AM or noon). If not then get there at least an hour early before the rodeo starts as you may be walking a ways and want to get there before traffic.
I believe there’s a club called the Hideout next to the Arena and the food vendors just outside the livestock show. Open from 6pm to midnight with live music at 10:15 pm after the evening rodeo concert is out.
Here’s a link:
http://www.rodeohouston.com/plan-you...-and-concerts/
Have fun! I’ll be there a couple times