All links point to AmazonSmile products. Same stuff and prices but they donate portions of the profits to your favorite charity. Also, This is just the stuff I use and I like, I don't have any affiliaition with any of these products aside from really liking them. There are tons of options out there and if you can, try them all! Find the equipment that works best for you!
Sakura Koi Field Sketch Kit. This is my go-to set. It has survived numerous family vacation, daily use, and so far it hasn't come up short. Its inexpensive, easy to replace colors and doesn't take up much space at all.
Prima Marketing Watercolor Confections. These come in some nifty cases and come in a couple different themed sets. The Pie set has some really nice metallic paints. Prima is a little more expensive especially if you want to get all of the color range and I haven't found any replacement pans if you run dry of a particular color but the paints themselves are solid and a joy to work with.
Kuretake Gansai Tambi. I literally can't pronounce anything in that title, but the paints are awesome and huge! It doesn't take much water to grab a lot of paint and they blend really well with just a wet brush. I'm still trying to master the amount of water I use with them because it seems if you use too much all of the pigment tends to settle in the corners of the painted area. BUT I love the range and the colors are super rich.
Copics. These are SUPER expensive, but are well worth it if you have the money and / or coupons. There's an insane amount of colors and then you can multiple that by the types of markers they have, you could spend a small fortune collecting these like they are pokemon. The great news is that they are refillable though. I started off with the cool grey set and shortly after started going to Copic buyer anonymous meetings.
Pencils and Miscellaneous:
Col Ease Red Pencils. These are my sketching pencils. Erasable, non photo reproduction Prismacolor red pencils. Soft graphite and really nice on a low tooth paper.
Castell HB Pencil. Not too dark, not too light, not too hard, not too soft. Perfect for sketching onto watercolor paper.
Uni Pin Liners. Waterproof and inexpensive! Ideal for lining / inking watercolor paper, set comes with a respectable range of widths but missing a brush pen. Comparable to the Micron Pen sets just a little cheaper.
Micron Pens. Waterproof and even more inexpensive. You can find these most anywhere, but the tips aren't as sturdy as my copic liners or my Uni Pins.
Canson Watercolor Paper. 140 lbs 300g cold press. Nothing fancy, cheap and readily available.