If I could go back to 1994 and speak to my 26 year-old self brewing his first extract kit, here is what I would say:
1 - Welcome to the hobby! To satisfy your inner engineer, you will likely spend thousands of man-hours researching, analyzing, experimenting, building and welding in addition to your brewing. Indulge yourself, it will be time well spent and be as enjoyable as the brewing itself!
2 - Move to all-grain as soon as you are comfortable and can afford decent equipment.
3 - Do not listen to anyone who tells you to relax, it is only homebrew.

4 - Do not listen to anyone who says "buy the plastic one", it is just as good for homebrewing. You will end up giving that stuff away and buying/building twice.
5 - Don't be afraid do dump a batch and start over. You can always buy "good beer" at the store.
6 - Invest time, money and energy into temperature control, especially for the mash and fermentation. You cannot brew great beer without temperature control.
7 - For every hour you spend learning about grain/malt, spend 4 on yeast, 2 on hops, 4 on water and 2 on recipe design.
8 - Never commit yourself to using one house yeast strain unless you have gone pro and even then I would encourage myself to forego it if at all possible.
9 - Forget bottling only, it sucks and will make you dread parts of your brewing process.
10 - I'm glad you built your own brewing/log software. The knowledge gained was immeasurable.
11 - Teach your sons to brew from a young age. Oh, never mind....good job!
12 - As soon as you can, brew four beers with the same grain bill, same hop schedule, but different yeast strains/fermentation temp schedule. You will be shocked at what you learn.
13 - Buy base malts in 50 lb sacks and store in 5g buckets in a cool dry place. You will be happy you did this.
14 - Learn how to prepare adequate starters right away.
15 - Learn how to can wort and prepare yeast slants, and then forget both until you retire and are bored for something to do.
16 - Buy Bru'n and be nice to Martin. He will help you with tons of knowledge on building water.
17 - Speaking of which, buy a decent RO system and learn to build your own water to style appropriate profiles NOT to city/region profiles. Every brewery treats its water, so matching city/region profiles is probably inaccurate, a waste of time and will inevitably lead to some bad batches.
18 - Create a log and record ALL temps, times, quantities, conditions throughout your brewhouse. It is one of the best ways to learn and the foundation for ALL troubleshooting.
19 - Never lift a full glass carboy without it being in a milk crate.
20 - Vaccuum seal and freeze your hops for storage. They will last a lot longer, taste and smell better and save you money in the long run.
21 - You won't listen, but buy a 15g boil kettle from the get-go.
22 - Three-piece valves are much better than two-piece and butterfly's are the bees-knees.
23 - Did I mention to never lift a full carboy unless it is in a milk crate?
24 - Racking and pouring both suck. Design your system/process to use gravity and pumps. Your back will thank you and your forearms will have less burn scars.