What is this post? Basically, we're going to Create or Modify your TexturePack's Existing Font.
Info pulled from

The Chat Font I use in Minecraft is from Misa’s Realistic Texture Pack. But I like to use a different texture pack.

I recommend the font from Misa’s pack (above). Download the default.png at this link / All credit for this font goes to Misa Realistic
You’ll need a default.png file to change the default Font of MC

If you do not want a texture pack for Minecraft, then you can use this TexturePack that ONLY HAS FONT in it. It will not touch the rest of Minecraft.

This guide is not on installing texture-packs, merely on modifying them for the Font system.

Step 1) Install your texture pack you want to use.

Step 2) When texture-pack is installed and working, close MC and open the Pack up (the ZIP file)
If you need a program to open your TexturePack then I recommend (free) 7ZipDownload

Step 3) Look inside the texture pack for a folder named “font

Step 4) If you already have a folder named font in the texture pack then skip Step 5

Step 5) Create a folder inside your texture-pack file called “font

Step 6) Open the font folder (if it exists already) and delete the current default.png file

Step 7) Add the (new) font image (default.png) to the font folder [Another words, drag and drop the default.png into the font folder]

Step 7) Once you have placed the default.png into the font folder, close the ZIP file and test it out (launch the game)!