Newbie gambler should first know his goal in gambling, if you’re into sports and already familiar with it then you can bet there as well and if you want to play the game on your own, you can also try casinos. If you really want to gamble, its ok to know both of this since playing casino games are quiet boring sometimes and if you have knowledge on sports, you can choose to gamble there instead. Newbies have to be more flexible, its good to have more knowledge and in gambling you should not be complacent in one game only. Learn gambling as a whole, this can be a big help for you.
Also, as a newbie gambler. He should ask himself if he's into fun or profit, this is where mostly are misleading themselves. They think that as a newbie, they've got the beginner's luck but all of a sudden, they realize that they're becoming habitual gambler and their main purpose is being forgotten.
A thing to remember when you're gambling, don't be too greedy. When you've made profit, take it and don't let the greed take it away from you.
I agree with this that newbies should ask themselves first if they were into gambling or just for fun. Most people who are newbies think this way that's why they ended up losing a lot thinking they could make a profit just by believing they have the beginners luck.
If I were the OP I would at least try each side on where do I do best, although OP did mentioned already that he found it easy on a sports games but for those who are in doubt which suits them try both games and see where do you play the best.