First of all you will need to know the number of calories you need to be in surplus, helping you to add mass. Your calorie needs depend on your age, gender, current weight and how active your lifestyle is. Work this out using the Maximuscle Bulking Nutrition Guide.
Make sure you get sufficient amount of sleep to aid your recovery; personally I have six hours minimum, which works for me, but everybody is different.
Alter your exercise routine:
If you’re working out three times a day training two body parts, try to spread it to six days working only on one body part per day. If you’re doing chest and biceps on Mondays and back and triceps on Wednesdays, make it chest and triceps then back and biceps. This puts more stress on the common muscle groups (biceps and triceps) forcing your body to grow more muscle fibres.
Whilst it is easy to think rest days aren’t needed you have to make sure they’re scheduled into your routine. You need to give your body rest days to recover, ready for the next big session. Trust me you will feel better for it.
Make sure you're disciplined with your rest period between sets, and a stopwatch is a great way of keeping track of your rest. Remember what you're in the gym for - it's not for a mothers’ meeting! You’re there to work on the best project you've been given… yourself.