As there's quite a few artists here, I thought maybe someone might be able to help me. I've recently bought some watercolour pens, I've never used watercolours before and I'm having a little trouble getting them to blend. Am I not using enough water? Do I just have crap pens? Is it just me? Any other tips would be greatly appreciated too!

I would suggest using some YouTube tutorials as a visual approach is always helpful! Otherwise I'd suggest just trying out a whole bung of different techniques and seeing which one works best for you [eg, adding more water, mixing colours before hand, layering colours, etc]

Without seeing the work, I can’t give you exact solutions but blending takes practice with application technique but also he amount of water and even the level of pigment affects the outcome.
You can mix the colors before hand and layering is always suggested. Make sure you have a heavily enough watercolor paper for that. Work in one area at a time (unless you are doing a wash then I suggest you get a large brush instead of a pen so the color is distributed evenly). Let dry between layers unless you can work wet on wet. You can use a hair dryer to speed things up but be careful to not let it push the water and color off the page.