As its your first i wouldnt go for a biggie on your back. It'll take hours, possibly more than one sitting and will hurt like hell. I have one on my back that took 3 1/2 hours in one go I was absolutely shattered, you loose a fair bit of plasma and will be very sore. Theres also the cleaning of it you have to do at least a couple of times a day, at first they are high maintenance. For me the shading felt like a hot knife cutting my skin.
All good fun.
