I'm sure you are getting tons of mixed advice, I'll tell you what worked for me to help keep me feeling full longer.
First, forget snacking, think 6 small MEALS a day. Fiber helps keep you fuller longer so the higher in fiber something is, the longer it will stick with you. Raisin bran cereal is higher in fiber than most other cereals. Kashi Go Lean crunch is awesome in yogurt or just with milk and it has a lot of protein and fiber.
Try making protein shakes before you workout. Blend up ice, water, protein powder and frozen berries, you can add yogurt or no sugar added frozen yogurt to it if you want it smoother.
Another good mini meal is a flax pita pocket bread with Almond butter and Polaners all fruit spread. bread -
Joseph's Middle East Bakery Low Carb Pita Bread has 60 calories for the whole piece, 2tbsps 180 calories and 40 calories for 1 tbsp of Polaners. This will hold you for a good 2-3 hours right on time for your next 'mini meal' and it's only 280 calories.
Nothing wrong with mozzarella sticks either, buy part skim ones, they have about 60 calories each, add some fat free ranch dressing with carrot and celery sticks and a hard boiled egg for another 'mini meal'. 1 cheese stick 60 cals, 1 cup carrots 50 cals, 1 cup celery - 20 cals, 1 hard boiled egg 80 cals = only 210 cals.
Try plain low fat greek yogurt with go lean crunch cereal and fresh berries in it. 6 oz yogurt - 60 cals, 1 cup of strawberries - 50 cals, 1/2 cup Kashi go lean cereal - 95 calories - 175 calories for another 'mini meal'
In 2 mini meals you've eaten 665 calories and Got in lots of fiber & protein
Plus you've eaten in 1/2 a day so far:
1 pita Bread
2 tbsps Almond butter
1 tbsp all fruit spread
1 mozzarella stick
1 cup of carrots
1 cup of celery
1 hard boiled egg
6 ozs of yogurt
1 cup of strawberries
1/2 cup of cereal
Hope this helps!