Plumbing/drilling etc help

[canadianbudz604]

Ok, so after completely ruining a 55g tank by trying to do stuff that I have no knowledge about, this time I'm looking for some help. I've got a 33g long (48x13x12) on the way and I am going to get it drilled. Now I have been trying to search up plans but there is not much that I can understand. Now this time the drilling will be done by a glass shop. What size of hole do I get drilled? I am going to have a 20g standard sump. The quietest most Dumass proof type of plumbing is what I want. My problem is I have no clue where to start