my portfolio is everythink iv done. Just take Everythink thats good uv have done, in my case i took lots of renderings of sketchs, also i took in some life drawing. U should ALWAYS add to your portfolio. iv collected sketchs from highschool > college > uni and it shows a big difference when u try for a job. Portfolio aint needs to be loads, but bascially have all your best going into it, also make it continious/flowing like in my case Architecture > interior design > Big scale > Small Scale. Start building your portfolio now, i have an A2 , A3, A1 size of them.