I have come up with a simple way of increasing skill levels without breaking the game or changing anything significantly.
Enter the Expert and Master
When you take a skill, you are classed as being proficient in it. Which is fine, but sometimes you want to be an expert or a master at a particular skill – maybe even getting known for it.
You can take a skill a second and third time (using skill slots at creation or when you level up – see below) to become an expert and master at a particular skill, respectively.
If you want to take advantage of this at first level, simply have a great backstory for why your character is an Expert or Master in that skill.
An Expert gains an additional +2 to all skills checks (as though his skill was 2 points higher), and a Master gains a +4.
When it comes to Tool Proficiencies, nothing changes with this.
If your character is using a particular tool and they are asked to make a skill check, then if they are an expert or master in that skill they get the additional bonus.
I use the rules in Xanather’s Guide which states:
If the use of a tool and the use of a skill both apply to a check, and a character is proficient with the tool and the skill, consider allowing the character to make the check with advantage.
So, for example, a character who is an expert with Deception and has the Disguise Kit tool proficiency makes a check to impersonate an NPC then she would receive an additional +2 on the check for being an expert, and have Advantage on the check due to the Disguise Kit proficiency.
In my campaign, I will allow PCs to become experts and masters sometimes during their downtime.
If you express a desire to gain a greater expertise with a skill, simply let me know and you can spend your character’s downtime training or studying.