1. Eat meals, not snacks. Snacking on crap absentmindedly is a great way to get fat. Get in 3-6 square meals a day, and you won't be hungry for snack foods. Some of these meals can be smaller, where some are larger. Taking a different mindset towards eating can make a big difference in your body composition. Eat with purpose.
2. Include at least 20g protein in every meal. Protein is very satiating, and will help prevent you from overeating unhealthy foods. If your only option for food at a given time is something low in protein, you can always have a shake before you eat. Steadily consuming protein throughout the day will also enhance muscle retention and building capabilities.
3. Eat "healthy" food whenever possible, 80+% of the time. 90% is better than 80. When I say healthy foods, I'm not referring to Oprah's acai berry products, or any kind of "superfood" or supplement (though protein powder gets sort of a pass since it's essentially food). I'm referring to simple vegetables, lean meats, whole grains, nuts, legumes, fruits, and dairy. Junk is alright from time to time, but shouldn't be a staple of your diet.
4. Get in at least 3 workouts per week. The only excuse is when you're on vacation.
5. If you're weak in a certain area, train it more frequently. If a body part or lift is proportionally weak for you, training it more than once a week is a good idea. When your frequency goes up, your intensity and volume per session have to adjust accordingly, however.
6. Do bodyweight exercises (in addition to weights). They will teach you coordination and body awareness while building strength, size, and endurance. They also serve as a way to keep track of your relative strength. Classics like push-ups, dips, pull-ups, hyperextensions, squats, and lunges are very effective. Adding weight is a great option when you're strong enough.
7. Don't extend sets past the point where you begin to compromise form. If you go to failure on a set, your "fail" point should be the last rep you can make without getting out of proper position. Don't contort yourself on a bench press, or round your back in a squat or deadlift. There's no point in being strong or muscular if you're injured all the time.
8. Include some degree of both cardio and lifting at all times. At any given time, you can be emphasizing one over the other depending on your goals. But you shouldn't completely neglect one for the other, as they can complement each other well.
9. Track your progress. This can mean keeping a workout log, a food log, or a journal, taking weight or measurements, or simply taking pictures regularly. It's easy to let your nutrition or training slide for an extended period, only to realize that you've made no progress or even regressed. Keeping track of things can help you figure out what's worked for you, what hasn't, and what reasonable adjustments you can make to spur on progress. Hold yourself accountable.
10. Don't sweat the little things. With the above in mind, don't stress yourself out over normal weight fluctuations, slight deviations from diet, or a bad training session. If you aren't training for a competition, these minor setbacks don't mean a damn thing in the grand scheme of things. Don't let a slip-up throw you off the rails completely. After an off day (or days), resume business as usual as soon as possible, and your slip-up will be negligible.
To expand on this point, you also shouldn't be thinking about the minutiae of diet and exercise when you still have 60 pounds to lose, or you're an able-bodied man that can only bench 155. It's easy to become overwhelmed by all the information out there, but the principles laid out above are all you need to get started.
11. Tune out the noise. This applies to many aspects of life.
Social media is filled with a lot of words and a whole lot of nothing. Some people love to tell others that they will fail, simply because they're insecure, and success makes them uncomfortable. Those people are nothing, and should be regarded as such. Do you think Tom Brady gets concerned over the armchair quarterbacks criticizing him on sports forums? No, he's too busy winning rings and spending time with his supermodel wife.
More specifically to health, fitness, and muscle, don't listen to the charlatans pushing products and promising outrageous results. If you've found something that you believe in, and that works for you, then stick it out and don't take on a "grass is greener" attitude towards other diets or workout routines.
This doesn't mean you should be close-minded. Be willing to continually develop your knowledge. But there comes a point where you need to stop second-guessing yourself, commit to something, and just grind it out. Don't let the latest article or study sway you. One study means precisely nothing, and an unsubstantiated article (like this one) means even less.
Choose a path, and walk it with confidence.
