Same as me. I have the same problem too. Just practise more. I usually spend a few days and hours to practise before I go to interview. I scripted it and rehearsal. I write them in the phone and memorize them. When I stuck in the jam, shower or at gym, I will practise.

Just keep practicing. It will be better after a few interviews. I used to practise for a few days and 1 to 2 hours a day for 1 interview. I started with writing all the answers for all kind of standard questions down and keep improving the answers. I read them out loud in the car or in front of my family and mirror. I keep the same note for many years (more than 10 years) and reuse it for every interviews. Now I don’t practise much, usually just review the skills they look for.

I don’t think I speak very well yet but at least I can self intro for 30 mins confidently.

You are welcome bro.

Usually I will lead the interview. I will shape it so that they can ask what I want them to. I will cover most of the standard questions in the self introduction and make a lot of hole/trap for them to ask what I plan, for example

"... I use Angular in my current job too. I witnessed the transition between all versions, from Angular 1 to 2 and now 4. I saw that one of the job requirements is AngularJS, so what version do you guys use here?"

That's a "trap" for interviewer. Depends on how they answer, you will have the chances to say 1 of these:

"Seriously? Angular 1? John, you miss the fun man, how can you not use the bootstrapping and the controller? blablabla How do you guys solve this problem in Angular 1? blablabla"
or
"Perfect! you use the mix of 2 and 4, they are the skills I'm confident with. I recently just complete a website with Angular 4. If you don't mind, I would like to show you some of my work. You can go to this link: blablabla"

Make it a conversation, lead them to where you want them to be rather than answer and full stop.

The most important thing is make friend with them, so that after the ice breaking part, when it's warm enough, you can say something like

"Come on, seriously? 5 years goal? 1 year ago bitcoin was still 1000 and now 18000, 2 year ago when I left my job we were still on Java 7, last I checked it's already 10! We are in the digital world, things changed so fast that what we plan 2~3 years ago are no longer valid now. My goal was to become a COBOL guru when I just graduated but I no one is using it nowadays. 5 years goal? Hmm... I've to start thinking now. I don't even know what I want to eat for lunch (make sure they know it's a joke, if they don't, tell them "i'm just joking"! And make sure it's warm enough to add these "humor" and "lansi" stuffs, if not it will become quite embarrassing). Having say that, I do have a life goal but it's not 5 years, I don't have a time for it, well, it looks more like a jinx than a goal. I'm a Chinese, Chinese culture is inherently more materialistic. There are 3 things that Chinese worship, longevity, good fortune and more money. Yes, MORE MONEY. We are money-centric. To be frank, all our goal evolved from this. Let's look at the standard answers on Google, you do know we can google all this standard questions right (With a smile on the face)? Let's look at each of the "best answers", which one is not indirectly or directly related to money and power? Why we want to work? Why we want to become a CEO? Why we want to become a Photoshop guru? Which one is not indirectly related to money and power? blablabla... In order to achieve this goal, I will have to break them into short term goals... blablabla... "

All these can be googled. Change them to your own answer, be yourself and keep rephrasing and fine tuning it. You will success.