Which one first? The one that has the better teacher. One is bound to have a better teacher. You always want the best teacher you can find in any martial art style you choose. A good teacher will make all the difference and largely also determines how good you will be. So check out both schools and see which students are the better practitioners because this is what you will look like when you study there.
Before jumping into the next style do make sure that you have a really good foundation in one style and know how to incorporate things into your foundation. Martial arts is not a collection of tricks. That is a really bad way to learn and fight. But if you understand the basics and principles and can incorporate new things into that foundation then learning becomes a lot more efficient. Not everything will fit together and you safe a lot of time if you can tell what fits and what does not.
Karate is easy to learn and geared toward kids, it might be a good staring point.
Karate.
Brazillian Ju jitsu. Better then Judo for self defense.
If you want to get good at them, either
a) Do one until you get a black belt in it, then do the other one or
b) Take both, but be prepared to progress slowly in both of them.
Do not consider yourself to be "any good" until you get a black belt in it. The worse thing you can do is get to about green belt----or lower, and think you know the style. In fact, many martial artists are of the opinion that even a 1st degree black belt barely knows the style they are doing.
One warning: I would not tell the karate people you are studying Judo, or the Judo people you are studying karate unless you know for sure they are not against cross-training. Why? Some people are style purists and may hold cross-training against you. Did I say ALL? No. I said SOME. Since you won't know who is a die-hard purist right away, it's best to act like whatever style you are in class for at the time is the greatest thing since oxygen.
I'm going to do karate and judo but what one should I do first was going to do judo till I get good at it then karate I'm 16 to
