I've been coaching for 5 years, at the freshman level, boys - and the others are right, keep it fun, but let them know that there's times when you get down to business. Correct fudnamental flaws early - don't let them practice bad habits, because it just makes it worse (i.e. now is the time to correct the kid w/ the corkscrew release - by the time he's a 10th grader, its wayyyy too late) remember, practice makes permanent. Another thing I try to do is let kids play different roles, i.e. don't have a 1st team and a 2nd team, it creates dissention - throw every kid a start, or better, give them a chance in practice to earn a start, say rebounding is your focus for the day, say whoever does the best job boxing out in practice gets an automatic start, and then really give it to the kid who does the best job - if you want it to be quantifiable, it can be how many rebounds a kid gets in a drill
but yes, good luck, the rewards are awesome - I lost every game of my 1st year, won 75% of them my 2nd, so you'll go through your ups and downs depending on the team - but the younger kids will run through a wall for you, and its awesome