What I am going to describe is my current "leg day" workout. My usual week looks like this:

Monday - Pull (Back/Biceps/Rear Delts)

Tuesday - Push (Chest/Delts/Triceps)

Wednesday - Legs

Thursday - Rest/Cardio

Friday - Pull

Saturday - Push

Sunday - Legs

Expect this routine to last 50-75 minutes.

*note - I have not worked legs for two week do to a knee injury and I'm dying to get back to squatting! 

Warm Up

To start off my workout, I'll do some high rep-low weight sets of stiff leg deadlifts and body weight squats. I'm sure this makes no difference in performance but I prefer to wear sweatpants and a hoodie on leg day to really keep my body warm. 

Back Squats (5x5)

Always start off with this exercise as it is the focus of your leg day. I like going 5 reps for 5 sets on this as I really focus on building strength in this movement rather than build muscle (the other exercises focus on this.) Pretty much anyone can squat (only excuse I'll hear is that you don't have legs or a back problem) even if its only half way! Just do what you can do and push yourself at it!

As a novice lifter, I find myself adding 5-10 pounds a week on my squat and I attribute the success (so far) to the 5 x 5 style. 

Leg Curl Machine (3x12)

I might actually switch up this part of my workout as lately I've experience pains when on this machine. Nonetheless, it's a great exercise to isolate your hamstrings and really feel a good stretch thats hard to acheieve in the hamstrings. 

Leg Extension Machine (3x12)

Not much to say about this guy. Another great way to isolate your quads!

Ensure you fit in the machine properly to avoid discomfort or injury.

Leg Press (3x12)

Great exercise for the quads. I use to push alot of weight with this exercise until I stopped pressing from my upper foot and through my heels. Going through the heels forces the resistence to work your muscles harder and make them bigger!

Hyperextensions (2x10)

This is a weird one to put in a leg day! This exercise delievers a great stretch through your lower back, glutes and hamstrings. I'll usually grab a weight and perform the movement (just for something to grab) for only 2 sets. My lower back is usually pretty fatigued at this point and I simply do not have the endurance to continue. 

If you don't have access to this bench at your gym, you can substitute it with "Good Mornings." They hit the same muscles, I just prefer hyperextensions because I feel my form on good mornings is not as good as it should be after squatting. 

The HyperextensionCredit:

What, no calf raises?!

Of course this is just my uneducated opinion but, I just don't see the need for calf raises. I'm not a bodybuilder so I just don't care about how my calfs look! I'd rather spend my energy in the gym on strength building exercises for real life applications.  

If you want to include calf raises into this routine, then do it! Just do them at the end so your legs aren't taxed before all the other lifts.