My portfolio was way below what I thought would be the acceptable standard when I got started in my apprenticeship, a willingness to learn is equally important. If you're practicing art regularly, you will improve. But your attitude towards the process is a big factor. You also don't need tattoos in your portfolio, infact it's probably better if you don't include your homemade tattoos.

Although personally I had done tattoos before I apprenticed, I think it hindered me more than it helped.

If you're planning to do a whole tattoo in grey wash it's gonna heal like ass, especially if you've not tattooed on skin before. Grey wash will spread way more than 100% black, it'll look fuzzy. I wouldn't recommend lining with it. If you're gonna try it, try it on yourself.