Merit Badge Counseling: The Basics
Never meet one-on-one with a scout (This is for your protection as much as the scout's.) A scout must always have a buddy, but the buddy does not have to be working on the merit badge.
You may not make the requirements easier or harder than the requirements in the book, and you may not add requirements. If it is an Eagle-required badge and the scout cannot complete it as written, see information for scouts with disabilities for a substitute.
Every scout must fulfill every requirement, exactly as written
answer every question
perform every activity (check with wording of the requirement: Show, Demonstrate, Tell, List, etc. must be fulfilled as written)
Set expectations for the scout
When you will meet, and what is to be done
If a scout comes unprepared, then send him home and reschedule the meeting.
It is preferred that a scout should be in full class A uniform for the merit badge meeting unless the activity makes it inadvisable, such as he is going rock climbing or painting.
You should have a working knowledge of the merit badge skill (read the merit badge book anyway to make sure that the materials that BSA wants transmitted are transmitted)
Enjoy what you are teaching - If you don't enjoy it the scout won't either
The scout keeps the blue card in his possession until the merit badge is done.
Sign off the requirements as he completes them on the grid on the back.
Keep a notebook which contains the name of the scout and which requirements he has completed. If he loses his card, you know what he has done.
After the merit badge has been completed, sign and date the blue card as completed in 2 places. Take the counselor's record and give the others back to the scout to take to his troop. Keep your record so that if the scout loses his record he can call you to sign and appropriately date a new blue card for him. He needs them for his eagle application.
Be sure to use the current requirements. New requirements take effect in January
Scouts who have already started a badge under old requirements may choose to finish under the old OR switch to new reuirements, but cannot mix & match
Resources
http://www.scouting.orgjscoutsourcefGuideToAdvancement.aspx for Guide to Advancement
http://www.scouting.org/scoutsource/BoyScouts/AdvancementandAwards/MeritBadges.aspx
Lists of merit badges and current requirements