Can someone tell me about using tanning beds with fair skin?

I know I ask some obvious questions sometimes, but I learned a good lesson today about tanning beds and what my limits are. So, I was hoping there was someone who could enlighten me
I’ve got a vacation coming up and I’d like to wear shorts for it. I don’t wear shorts usually because in the sun, I do burn. I thought of maybe getting a base tan and go from there on my own. I’ve had 3 sessions the first two were for 3 minutes and the second was for 5. I am now mildly sunburned. I do mosturize before and after. I do everything the salon people tell me to do. I’ve never tried to tan before ever and I’m curious to know what I can do. Anything I’ve missed or anything special I need to do.