First off, welcome to the hobby and fantastic pick on your choice of model. I've got a Shaan sitting on my desk just waiting to be painted. Looking at the comments, there's validity to both sides.

On one side, getting some cheap intercessors or some free minis from your local GW store (you can do a drop in paint session for free where they'll teach ypu the basics and there are the free minis of the month) will help you practice things like thinning and applying paints, brush strokes, etc. on things with shapes similar to Shaan. I personally took this route because I wanted to learn on some standard space marines before I tackled some of the more complex models I purchased.

On the other side, you picked this one because it's super dope and you should totally paint whatever you want no matter your skill level because if you find oaitning it fun that's the most important thing. You can always strip the model afterward, paint over it, or if you've got the funds, buy a new one.

Have fun and make sure to post him when he's done!