battleforce upgrade

I am new to warhammer 40k and want to start a small 500-1000 pt. ork army. I bought the ork battleforce and a box of killa kans and warbikers that I found for half price. So I currently have: 20 ork Boyz 2 Nobs 5 warbikers + nob 3 killa kans 1 trukk What would be some things I should add to...