| Almost every kind of martial arts can be helpfur for you and TKD.|
Aikido is good too. It can be attractive.
I studied its precise history, related to that of TKD and Hapkido of Korea.
I suggest you learn every kind of martial arts if you can.
Additionally, it is also important for you to choose one and master it in deep level.
As a beginner, it is more helpfurl to try more kinds of martial arts.
As a professional(or blackblet) it is more important to concentrate yourself on a one.
The foundation of TKD will be helpful for Aikido too, someday in the future.
Especially, the essence of Kang and Yu is key point to understand those techniques.
I suggest you memorise some texts of TKDbible vol.2.(3JKY); the followings.
Kang: Its essential point can be summed up by a word, "concentration".
In order to accomplish concentration you should cower your entire body down when you move. This Cowering is the first condition of Kang-technique in Taekwondo.
This cowering is in itself the concentration of all parts of your body. The foundation of cowering is to lower your pose.
The second condition of Kang-technique is possession of weapons to concentrate. The process of training to get them is called "Hardening."
Yu: Its essential point can be summed up as, "following your opponent".
In order to use Yu-technique you should relax your body removing excrescent force.
In order to be able to use Yu-technique you have to know the network of techniques This is the second condition of Yu-technique.
Also should you know what you have to follow and what you have to keep in order to use Yu-technique. This is the third condition of Yu-technique.
When you practice Aikido, you remember texts of Aikido.
In every martial arts, the basic is most important.
It is more important that techniques, because the basic make technique possible.
Everyone come to be attracted by good looking technique but not its basic.
For basic is hard and boring to practice.
And this is why so many people practice TKD but fails to get its true power.
So I wish you are determined to accept hard training of basics.
In my case, I exercised the basics of TKD for 3 years.
These days, almost no one practice that way. It is classical way of training.
It is key point of training to practice hard training for sel-defense.
And the following is the first training that I suggest to you.
It may be hard for you first, but it is very important, so that you should practice for sure.