How do you rate commissions?

I don't know how much will i charge my cilents

I first analyze the commission I will have to do, then what the client wants, and what I can do. Always good to have a conversation with the customer for this

If you are fine working with an hourly contract, it can be straightforward to establish an hourly rate where for every hour you work on the commision, you charge the client a certain amount. This helps if the scope of the commision scales and if the client wants continuous additional changes. It can also help to set a do-not-exceed limit beforehand with the client if they need to work within a specific budget.

Local industry standard rates or consulting peers should help determine which rate to use for which kind of project or commision.

always always always ask for budgets first

I'd say, look around for people who have the same style/art level as you do.
For example, a professional artist as Marco Bucci would ask for a lot of money for sure; but that amount of money is justified by the super-high-quality stuff he's producing.
We can't say the same thing for a beginner or someone who's still struggling to learn.
You'd need to check your level and then go on.

It has never been an easy issue for anyone, but I will tell you that your interest in participating in the project has an impact on the price. Depending on your interest in the project, the price should be higher or lower.