Let me start with this. I hate Crossfit. You may ask, "Why would somebody hate such an athletically designed program?" Well, It's simple. Firstly, they have several WoD's in which you're supposed to do sets of 10 in Olympic lifts. For those of you not in the know, Olympic lifts are highly technical. I refuse to go higher than 5 reps on both Snatch, and Clean and Jerk. Second, they don't simply condone poor form, they teach it. Crossfit loves it's kipping pullups and other "Explosive" versions of exercises. But quite honestly, they're a waste of your time. You should never use momentum to move the weight, exception being Oly lifting, weight should always be muscled up. And my final gripe is their random workouts. All I have to say is, Random workouts, random results. Consistent workouts, consistent results.
All that being said, it's easy to see that I follow an older strength philosophy. I hate machines, I hate curls, and I hate gloves and pads for lifting. People want to get stronger, but they're not quite sure how. So they go to a chain gym, avoid the free weights except for curls and maybe bench, and they wonder why they aren't getting stronger. Real strength is put on by doing heavy compound lifts, I.E. Squats, Dead lifts, or bench. Don't waste your time on anything but barbells and dumbbells. I know I sound like a meat head, but I'm just tired of seeing people using dumbbells exclusively for curls, isolation machines, and other isolating exercises. Don't get me wrong, it's okay to isolate a muscle. I like to work my ham strings by doing Romanian Deadlifts, but Isolations should make up less than 25% of any workout.
Now my favorite part, nutrition. If you've ever been into a weight room or gym, you'll know that protein supplements are widely available and used. I recommend their usage to anybody trying to put on muscle mass. however, don't fall victim to the protein craze. Too often I hear people brag about protein consumption, or how much money they spend on a given protein supplement. What they forget is that a supplement is just that, a supplement to your diet. Most of your protein should come from meat, fish, dairy, or nuts. Then you wonder, "How much protein should I consume per day?" That's an easy question. Aim for 1 gram per pound of body weight. Coupled with optimum rest and training, your gains will be fairly linear.
Here's a dirty secret of mine, eating more food (Calories) than your body requires will substantially help you increase your strength. As to the science behind it, the dumbed down version is that a Calorie surplus allows more energy to be put towards repair than what is usually allotted. To give you an idea of how much to eat, multiply your bodyweight by 16 and add 500. This is the amount of Calories that you must eat per day in order to add muscle much faster than eating at your body's required level. Assuming that your nutrition, training, and rest are sound. you could put on anywhere from .5 to 1 pound of muscle every month. Now if you're younger this number might be more like .75 to 2 pounds every month. That's quite a bit in a short amount of time.
I've used the word "Training" in here several times. What I really mean is routine. Fortunately for many athletes, a coach will likely provide a routine to follow. For those of your freelancing, Here's my favorite two: "Starting Strength" By Mark Rippetoe. It's a book that you can find online for about $30 new. This is designed for people new to lifting.
Then there's the "StrongLifts 5X5". This has you doing compound exercises and will put on appreciable amounts of strength in a matter of months. Here's a link:
http://stronglifts.com/stronglifts-5x5-beginner-strength-training-program/
A little off topic from the rest of my post, but what are your guys' favorite lift(s)? I'm having trouble deciding between squats and hang cleans. One builds strong legs, abs and back, while the other hits just about every muscle, but is highly technical.