The problem with machines and that most enforce 'bad' form. Every person has their own natural motion that a machine simply cannot match.
The best way to learn a free weight exercise is to simply start doing it without any weight. Start squatting and dead lifting with just your body weight (use a broom handle to simulate the bar). Once you get that down start adding weight. There is a very little that a machine will do to help you with exercises like that and in fact it could end up enforcing bad habits.
TAKE VIDEOS. If you're hesitant to bring a point and shoot to the gym, go later at night or before noon when the gym is relatively empty. Share your videos on any of the big lifting forums and ask for opinions. Sure, you can ask a trainer, but if you're lifting at any of the major chain gyms I wouldn't trust a lot of those guys to critique a squat as far as I can throw them.
If you're doing a lift with improper form, you might as well not do it at all. The point of maintaining proper form is to not only remain injury free, but to also point out any strength imbalances you might have (weak quads in a deadlift, weak lower lumbar in a squat, etc etc).
(example vid, i switched to sumo-stance for deadlifts and wanted to make sure i was doing it right before moving back up in weight -- http://www.imperial.org/~jd/deads275.wmv )
I can respect -anybody- that posts videos and asks for help on form. The amount of weight you're moving is trivial - the fact that you want to focus on your form and perform the lift correctly speaks volumes. I respect the guy squatting 95lbs correctly infinitely more than the guy squatting 405lbs to 25% depth any day of the week.
Great advice! The 2 angles you generally want for a video are the front or back and the direct side angle.
Luckily I haven't had to post and vids because I have a trainer friend who is very good at form and correction. He just adjusted a few things in my DLs and I'm closing in on 500lb DL again.
I've tried sumos off and on, but I don't they are right for my body type. I have long arms and legs and I just get so much more leverage with the traditional DL. I do sumo holds though as accessory work to keep my glutes firing properly.
And yea, the guy quarter squatting is generally a dumb ass. There are times to quarter squat, but for most people they should never need to.
As you and others have mentioned, deadlifts, squats, presses, and bench press are the most effective and time efficient. Don't waste time on bicep curls and other isolation exercises.
Good form is vital though, so get 'Starting Strength' by Mark Rippetoe. There are plenty of exercise books available, but this is the only one I know of which will spend 50 pages explaining the proper form for the squat. There's even a companion video for the book.
I also got the "Starting Strength" book. It's very thorough on the technique of all the basic lifts (squat, bench press, deadlift, overhead press, power clean).
It doesn't they very much about programming (i.e. how to and how much to increase the weights you lift), but you can get advise on these from other sources.
Yes, and I may even get it, now that I have probably started reaching the end of the beginner stage where a super simple program suffices. (I squat 1.5 my body weight.)
The best way to learn a free weight exercise is to simply start doing it without any weight. Start squatting and dead lifting with just your body weight (use a broom handle to simulate the bar). Once you get that down start adding weight. There is a very little that a machine will do to help you with exercises like that and in fact it could end up enforcing bad habits.