I'm only a DIY'er but did the same a while ago.
I got good results using an MDF primer http://www.toolstation.com/shop/Painting%20&%20Decorating/Primers%20&%20Undercoat/MDF%20Primer/d150/sd3006/p50498
I sanded with a orbital sander, primed the MDF and edges, lightly sanded again.
To...