I have to admit being the "not so into classes" type. I have taken dogs to classes only when preparing for obedience work.
Training I keep to about 5 to 10 mins TOPS, depending on age. It depends on what I am teaching. If something complicated, I break up the steps and work til each step is mastered to do the next step. I do a quick one or 2 repeats a couple of times a day to reinforce. I use meals and treat times for reinforcing.
I must admit with my Rotties and chows, they never got food without doing a command. Not so strict with the basenji.
I just posted this link but will do it again.
http://www.clickerlessons.com/index.htm
You can write Mary if you have questions (tell her I sent you). She is utterly clear. I still laugh because once she was fussing about how people have command words, then their REAL command words. I am noticing I have slipped on "come." I always say "come" and then go get the dog… but I have caught myself saying to Cara "DON'T MAKE ME COME GET YOU!" and it has, indeed become the real command. So I have to change that.
Like Andrea, "leave it" is one of my top. I also teach "look at me." Again, not quite so critical with a small dog you can hoist out of trouble if need be... but with my Rotties and Chows, they learned to lock their eyes on me, ignore EVERYTHING (usually a rude dog) else and let me handle things. More than once at shows or in public it helped prevent them engaging. I used it instead of just "leave it" because I wanted a specific response... not just stop but to actually put their focus on ME.
I like adding tricks into regular obedience. Changes things up, is often fun.