All you need to have to start a Journal is a Notebook and A Pen. If you are new to the Journaling world, start from the bottom, you can buy some cheap compositions notebooks rather than buying an expensive notebook intended for journaling since you are still new. 

You can also use a graphing notebook like me, it's really hard to find a blank notebook in my city with the perfect size I want. I'm not new to the Journaling world but I keep on transferring or changing my journaling notebooks whenever I feel like it. 

I love to use the graphing notebook because it's easier for me to make some checkbox, etc. etc.

I'm not discouraging you to buy a notebook intended for journaling but knowing the fact that you are still new, you should start from the cheapest notebook to the expensive one because if you don't like it it's really not a waste of money.

You will also need some pens to right? Like you need to have some pens inorder to write something on your journal. I love using some gel pens w/ the tip 0.5 or 0.3

If you want to add some pop of color on your journal, then you can invest on buying some colorful gel pens. The ones that I have are not branded, but they work pretty good plus they are cheap! I'm planning to buy the expensive colorful pens if I'm consistently journaling. Again it's really good to start from the cheap ones because it won't be a waste of money if you'll stop journaling.

These are some things that I consider "OPTIONAL THINGS". These aren't that necessary but if you want to have them then go!

WATER COLOURS - You know how much I love watercolours right? I bet you don't know that. Watercolour is one of my favorite medium when it comes to art. it adds a pop of color to your journal too!

COMPASS - I'm a huge fan of drawing circles for the date today, month, etc. but I can't draw a perfect circle freehand! So having a compass is really a great thing to have.

RULERS, PROTRACTORS ETC. - Also like to make some geometric shapes on my journal so these come handy.

STICKY NOTES & GLUE STICK- These are probably the ones that I really don't use that much when it comes to journaling but I still want to have them because who knows when will I need then right?

Papers, Stickers, Inspirational Sayings - Your can print out some good inspirational sayings online or just by looking at your magazines is also a great way to spice up your journal. Again, I don't use them that much but it's good to have them on hand.

MARKERS, WAX CRAYONS, HIGHLIGHTERS - These are very essential to me when I want to pep my step in journaling! Wax crayons aren't then best medium when it comes to the grown ups but I love them okay? I prefer Crayola Wax Crayons in 64 colours/shades. You can go crazy just by looking at them and also just by smelling them, it brings you back to your childhood memories right?

Highlighters are also a must for me in journaling, if I really have something to do or need to be finished that day, I would highlight them and because of that, when I open my journal it's the first thing my eye catches and makes me remember I need to do it right now.