Can you please suggest how to usen snowball and avalanche at the same time?

It's a wrong approach. You should either follow the debt snowball method or the debt avalanche method. You shouldn't follow both the methods at the same time. In a debt snowball method, you should make minimum payments on all your debts. But you have to make extra payments on smallest debt every month. You have to continue to do it till your smallest debt is paid off. Once your debt is paid off, you can focus on the next smallest debt. Your goal should be to pay off debts from smallest balance to highest balance.

It will not work. If you have less money in hand, then go for snowball method. And if you have good cash flow, then you can tackle the avalanche method easily.

You should choose either debt snowball method or debt avalanche method! But I would suggest you to go for debt avalanche method.
At first you have to pay the debt with the highest rate of interest. After paying it off, target the second highest interest debt. You have to continue paying this way until all your debts are paid off. But make sure to make minimum payments to other debts at the same time. Initially it will be tough for you to pay off the highest interest debt and it will take comparatively more time. But at the end of the day, you will get rid of your debts fast and save more dollars as the highest interest debt is getting paid first!

I think it's up to you. You can follow both the strategies at the same time. How? List your debts with the rate of interest and the outstanding balance. Now choose 2 debt accounts from the list - one with the highest interest rate and the other with the lowest balance. First of all, make minimum payments on all other debts and extra payments on these 2 debt accounts. This way, you'll repay the one with the lowest balance fast and the highest interest rate one also relatively faster. So, you'll save the interest payments too.