My tips:
Read through as many threads in this section as you can. I think i read pretty much every thread before getting rats.
Next make sure you buy high quality rodent block.

And most important, find a feeder breeder with healthy, friendly stick to buy your starter group from. Would of saved me a lot of time if I did that in the first place. My first group turned out to be biters. My stock from other breeders are very friendly.