I did these when I was searching for a job. It was a painful journey of rejections. But I finally got it.
For interviews I would first start practicing HR interview questions. Then when I get comfortable about answering those questions I move to participating in coding competitions.
Then I set up a mock interview in a website called Pramp. It's really good for people who want to practice coding for interviews and the questions are really good.
In Pramp you have to attend 5 mock interviews then after that, a person from Pramp will contact you.They will help you to search for a job. It's really helpful.
At this stage you should actually be very efficient at coding in any language of preference. Next you need is interview calls. For that you would need to change your resume to see which gets a better response. You need to play trial and error game for some time until you get a good response from all types of companies big and small.
So I recommend you first finish setting up the resume then move on to the next step. These were the very few of my experiences preparing for interviews.
Just Keep you head up always because in the journey to get a job you will face a lot of rejections.