Crisis Core: Final Fantasy VII/Missions

Aside from the main storyline of Crisis Core, there are 300 missions to take part in. The Mission Menu can be accessed from savepoints, and missions are sorted into categories and sub categories. You can also record your Mission Progress with the percentage in the corner of this menu.

When you open a sub category, you get a list of available missions. Each of these has a rating based from your level.
 * Very Easy - Very simple missions that you will have no problem completing.
 * Easy - Also quite simple missions, that can be easily done at that point in the game.
 * Normal - Average missions, that any decent Crisis Core player should be able to complete.
 * Hard - More difficult missions for more advanced players of the game.
 * Very Hard - Rather difficult missions. Some of these, upon unlock, are impossible, as this is the highest difficulty setting, but the majority can be won with technique, and not stat differences.

Below is a complete list of missions that can be completed, by category:

Shinra's Basic Training
"This is a simulated battle against infantrymen. The difficulty level is set low, so it should prove no problem to a SOLDIER operative. Relax and enjoy the training."

Just attack. These are the same as the Sentries at the beginning of the game, so it should be no difficulty whatsoever.
 * Reward: An Elixir

Shinra's Advance Training
"This is a simulated battle against Shinra's new Gun Bull Heads. You may have fought them before, but that doesn't necessarily mean that the fight will be easy. Overconfidence may lead to death..."

No special strategy should be required by the the time this mission is unlocked.
 * Reward: Hero Drink

50 Shinra Troops
"You will be sparring with out infantrymen. Although each individual posses little challange, the fact that they will appear in a constant stream should even the odds. Let us see how you fare."

The easiest way to deal with the crowd is to use materia such as High Jump or Assult Twister+, which allows you to hit loads of enemies at once.
 * Reward: Hero Drink x2