A good summary of your character progression is given as a table for your Class in the Player's Handbook. Use this to see at-a-glance how your character is going to get stronger as you level up!
1. Ability Improvements: Every Class gains new ability scores at 4th Level.
Option 1. Choose ONE Ability from STRENGTH, DEXTERITY, CONSTITUTION, INTELLIGENCE, WISDOM, CHARISMA Raise your chosen ability score by 2 points Option 2. Choose TWO Abilities from STRENGTH, DEXTERITY, CONSTITUTION, INTELLIGENCE, WISDOM, CHARISMA
Raise each of your chosen abilities by 1 point
Be sure to adjust your ability modifier if raising your ability score is enough to meet the next threshold.
For example, if you raised your STR score by 2 points from 14 to 16, your modifier changes from +2 to +3.
See Player's Guide, p. 13 for a list of Ability Score thresholds and modifiers.
2. Proficiency Bonus. At 5th Level, Your Proficiency Bonus increases from +2 to +3 Be sure to change your proficiency modifier for your skills. Where you've written +2 in the skills section of your character sheet
this now increases to +3. (If you're playing a Rogue, remember that your Expertise trait allows you to double your proficiency bonus for a few skills. Make sure you increase those skills to a very handy +6 rather than +4)
3. Class Benefits: Some classes gain new perks and abilities at 5th Level. Consult the Player Handbook for information about what
benefits your class gets at Level 5. If you're a spell caster, refer to the table for each class to work out how many spells and cantrips you can know at level 5.
Select new spells as necessary.
Refer to the same table for other stats (e.g. Sorcery Points, Rogue Sneak Attack Bonus)
That should be it! Look forward to meeting your new, stronger, characters!