Thanks! But, uh, where exactly should I go, then? My routine used to be upper body one day, lower the next (so everything gets worked 3X per week), but now I do one full-body on Fridays and split a second over the rest of the week. But yeah, where should I go if not to failure? How will I know when to increase weight?
You will know when to increase weight because it will start getting easy. Over time you will be making gains. Or you could get yourself on a program with good progression. I think you should take your max lifts and get 65% of all of them. Do a full body workout, 3x a week and do 3x8 or 3x10 whichever works for you. And then every week progress by adding another set or adding more weight. There are many ways to progress.
You can progress weekly by
Intensity (The amount of weight lifted)
Frequency (The amount of time working out per week)
Volume (The workload of the lifts multiply sets by reps)
So for example for intensity progression you could add 5 pounds to your lifts every week. For frequency you could add another workout every 2 weeks and for volume you could add another set to your lifts or more reps. Also make sure to change your program every 3-4 weeks. To change your program simply change the exercises around but keep the fundamentals the same.
On the full-body workouts your main lifts should include
Horizontal Press (ex. bench press)
Horizontal Pull (ex. rows)
Vertical Press (ex. military press)
Vertical pull (ex. powerclean)
Quad/Glute Push (ex. Squats which you should always include)
Ham pull (straight leg deadlift)
And then accessory work that includes the core area, forearm, and calves. I don't recommend working out the biceps or triceps. The triceps get plenty of work from the military presses and bench and biceps get plenty of work from big back exercises like the rows. For calves you can do calve raises and seated calve raises and for the forearm you can do wrist curls or hammer curls if you prefer.
For the core make sure you target every area. This should do it:
Planks
Side Planks
Crunches
Side Crunches
Leg Raises
Back Extensions
And a twisting motion with either cables or a weight (be slow and controlled when doing this).
Like I said earlier if you want to add muscle eat more then you usually do; in good food though like Chicken, Tuna, and Oatmeal. My favorite meal of the day includes a whey protein shake with 2 cups of milk, Oatmeal, and a Apple.
Here is a exercise directory if you don't know the exercises I'm talking about:
ExRx Exercise & Muscle Directory
Good Luck with your goals. If you need any more info I will be here to help.