On your turn, you can move any distance up to your speed. That movement will generally include running, jumping, positing yourself around an enemy, climbing over things, swimming, flying, or other movement actions. You may use your total movement distance at any point in combat, breaking up some of up before or after other actions, if you wish.
Drinking a potion takes a movement action, though you can also perform it as a standard action. That means if you are standing still, you can take a standard action, like attacking, and drink a potion in a turn. You can even drink two potions in a turn if you use both your movement and standard action to do so.
As a movement action, you may attempt to fool an opponent into believing you will make a melee attack, causing him to create an opening that you can exploit. To feint, you make a Deception check against your opponent’s Insight. If successful, your opponent is Flat-Footed until the next melee attack against him, whether that attack is yours or an ally’s, successful or not. If you fail, you provoke an attack of opportunity. If you attempt a feint twice in one fight against the same opponent, each subsequent attempt is made at disadvantage. You can only feint a creature with an intelligence score.
Hiding may also be done as a movement action. This allows you to perform a standard action, then hide in place. Or vice versa. See Standard Actions.
As you move, you may interact with the world around you in minor ways. These interactions are small enough so that they can be done simultaneously with your movement, and generally you can do one (sometimes two) without slowing yourself down or requiring a standard action: Pick up an object, draw or replace a weapon, give an item to another character, push an object out of the way, take something out of your bag, open a door, or any similar interaction. If you need to perform one of these interactions, like swapping out weapons, then you need to take a movement action and therefore cannot perform a full-round action. After performing any of these small interactions, you usually still can move your entire movement speed.
Some spaces you move through will take half your movement due to difficult terrain. These may include, spaces with rough ground, bodies in the way, a friendly player in the space, a rope that needs to be climbed, a table or other furniture in the way.
Small obstacles (like a waist-high wall) not only take twice as long to move through, but they require a DC athletics check to successfully navigate. Failure means you trip, fall prone, and end your movement. Some obstacles (a rope to climb, a pond to swim over, a narrow ledge to balance on) might require continual Athletics or Acrobatics checks to navigate.
Any time you are off your feet you are considered prone. It takes 10 feet of movement to stand up, and this movement will provoke an attack of opportunity. If crawling while prone you move at half speed. Prone characters do not get attacks of opportunity. You attack prone targets at advantage with melee attacks and disadvantage with ranged attacks.