I have written several posts categorized under the #notebook tag. The posts cover drawing, adding pockets and foldouts, creating dust jackets and other aspects of using notebooks.

Regardless of whether you scrapbook, journal, bullet journal, take sketchnotes, augment written entries with drawings or simply doodle in your notebooks, these tools are essential.
Customize Your Notebook
Tools are essential for customizing your notebook. In my post Setup of a Pocket Notebook, I share various things that I add to every new pocket notebook. Most of these customizations require the use of the tools described below. These customizations enhance the functionality. What you need may be different, but take some time to consider how you can expand the usefulness of your notebook.
Buy What You Need/Want
When my daughter was in the early grades of elementary school we had to purchase school supplies using a list provided by the teacher or simply pay $25 for the teacher to buy all of the supplies. Once you’re out of school, you can buy the tools that work for you. The tools below are cutting tools, guides and other.
Proximity
The most important tip is to keep tools nearby, easily accessible. The old-fashioned pencil box is still a great idea. JetPens has a variety of styles and designs to store essential tools. You can add tools over time as you determine your needs and determine what works for you.
The Tools
CUTTING TOOLS – I use three cutting tools regularly. Scissors are useful for cutting small details or when something needs to be trimmed quickly. I also have a small cutting mat and a precision cutting tool (X-acto knife or generic brand ([e.g., Hobby Lobby]).
The final cutting tool that I use frequently is a paper cutter. Pictured below are two paper cutters from Carl.

GUIDES – This category of tools includes templates and rulers.
Templates. In the picture below are four templates. The upper left is a template that I designed and my dad cut on his laser engraver. Since this may not be an option for everyone, you can also purchase ready-made templates from an art supply store. The green Alvin template (upper right) cost about $7.00 and fits in the back pocket of a 5.5×3.5 inch notebook (pocket Moleskine). The lower images are different versions of the same template – a set of guides for lines. I first design and constructed the template from card stock (right) but then had it cut commercially (left) as part of a set of templates.
Rulers. Keeping a ruler nearby on your desk is convenient, and for this purpose I keep a plastic 6-inch rule in a pencil case. I also discovered a bookmark ruler that magnetically fastens to a page. Unfolded, it is 15cm (about 6 inches). From time to time it may be handy to print a rule. The printed ruler pictured below is from Printable-Ruler.net. A 12-inch (30cm) printed ruler can easily be folded and stored in the back pocket.
OTHER – Just because “other” is a catch-all category, it is not a lesser one. All of the included – glue, writing utensils and self-adhesive notes are essential.
Glue. An archival quality glue stick is necessary to glue papers and envelopes into your journal. While other types of adhesives are available, the glue stick is clean and easy to apply.
Writing Utensils. These pens and pencils (and an eraser) represent the many pens and pencils I have available to use. I selected these because this is the minimum set of writing tools: tool for coloring (pencil, pen, marker), fine liner for black lines, a light blue pencil for creating guidelines and a standard #2 pencil. The erasers on mechanical pencils don’t erase cleanly for me, so I keep a large eraser nearby.
Self-Adhesive Notes. Also known as Post-It notes (name brand) and sticky notes, self- adhesive notes are useful to bookmark pages, good for quick brainstorming and a way to give someone else a note.