Firstly, congratulations on doing work which your friend wants to pay you

Secondly, do not be afraid to charge him like any other client. Friend is friend, business is business.

Thirdly, there isn't a standard rate. Some fellows charge RM500 (or less), and some charge RM1000++. How you should price your services is the value of your time at the level of experience you're at?

For example; if you're a designer with less than a year experience. Starting with RM10 or 15 per hour is alright. Then when you take into consideration the time utilized to conceptualize, design and etc, you'll get your estimate rate. But don't stop there, think about whether it really pays your bills - utility, petrol and others. If it doesn't, add on a little more before telling him/her what's your price.

Hope this helps.

Congrats.    Some charge cheap, but some charge expensive. It all depends on what you think how much your time worth.

p/s: I need logo design too, PM me and we can nego