Do you have a recipe in mind?
For more bitterness add more hops at the beginning of the boil. Hops need to be boiled for about an hour or so to produce the bitterness. The bitterness is produced better in a less concentrated wort, so you could also consider doing a "full-boil". For more hop flavor add more hops about 10-20 minutes before the end of the boil. For more hop aroma add them in the last 5-0 minutes or even dry-hop (add hops to the fermenter at the end of fermentation) for 1-2 weeks before bottling.
For more alcohol you can add more malt extract or even sugar. The homebrew recipe of Pliny the Elder has a pound of sugar in it.
Welcome to the obsession (oops I mean Hobby, yeah tht's it).