I've done this many times. Some guidelines for my process are are:
Use beers that aren't too strong, <6% is good.
Fresh bottles are better, as the dregs are more viable.
The more bottles used, the better. I might have a couple, and see if the wife wants to drink one with me.
Be sanitary as possible.
Have some nutrient in the starter. Shake it to aerate.
Make sure the bottling strain is the same as the primary strain.
Others will have their own options on how to do this.