Hello!
The two most common reasons for lack of results are overtraining and poor exercise selection/performance.
People overtrain by not allowing at least 72 hours between workouts involving the same bodypart. Note that things like sprinting are leg workouts so do them on the same day as your leg routine.
In general, your strength training sessions should last no more than 40 minutes with 20 minutes being preferred.
For strength gain without size, pick a weight that is 85-95% of your one-rep-max [1RM]. Most people can ususally lift this 2 to 5 reps. This should only be done with experienced lifters as it is hard on your body.
For general strength/size gain, pick a weight that is 80-85% of your 1RM. Most people can usually lift this 5 to 8 reps. Note that the biggest correlating factor in strength is the size of the muscle's cross section. The bigger the belly of the muscle the stronger the muscle.
For general recovery ability, pick a weight that is 65-75% of your 1RM. Most people can usually lift this 8 to 12 reps. This will enhance general lactic acid neutralization. It will not "tone."
Repetitions of 200 to 500 reps will build muscular endurance. Do bodyweight or no-weight exercises for this.
In general, no more than 3 sets of any particular exercise and no more than 5 sets for any body part (example: Chest--3 sets of bench press and 2 sets of chest flyes). Rest between sets should be between 25 seconds and 75 seconds. Shorter rest will "fill-out" the muscle while longer rest will "bulk-up" the muscle. You will need to use less weight if you choose a short rest time.
Usually the harder but less frequently you workout the better results you will have. Remember, the key is progressive overload. Doing 6 sets of 20 is like starting your car in 4th gear.
A popular "split" is to do the following...
Wk1/Mon: Legs/calves (Legs)
Wk1/Tue: Lats/Biceps/Rear Delt (Pull)
Wk1/Wed: Chest/Triceps/Front & Side Delt (Push)
Wk1/Thur: (Rest)
Wk1/Fri: Legs
Wk1/Sat: Pull
Wk1/Sun: (Rest)
Wk2/Mon: Push
Wk2/Tue: Legs
Wk2/Wed: Pull
Wk2/Thur: (Rest)
Wk2/Fri: Push
Wk2/Sat: Legs
Wk2/Sun: (Rest)
Wk3/Mon: Pull
Wk3/Tue: Push
Wk3/Wed: Legs
Wk3/Thur: (Rest)
Wk3/Fri: Pull
Wk3/Sat: Push
Wk3/Sun: (Rest)
Abs are done on Mon/Wed/Fri. See how bodyparts cycle between 2 times a week and 1 time a week?Week 4 would look like week 1. Wednesday is a "heavy day" where you would do negatives or descending sets. All other days would be concentric only.
Rest at least 1 day a week, 2 days a month, and 3 weeks a year (or three 1-week rests).
Muscle "tone" is merely residual tension in the muscle due to posture, musculature, etc. Whether or not you can see this "tone" is subject to the amount of bodyfat around that muscle. There is no way to selectively reduce that bodyfat...you need to reduce your overall bodyfat and your body will select where it removes fat according to your genetics.
Adapted from Health for Life (http://www.healthforlife.com)
HTH,
James
P.S. I highly recommend the Health for Life books. Best exercise science out there...for athletes and body builders.