Clean and sanitize. Always.
If you follow the advice posted and read the noted books, you'll have a good brewing session.
I agree, trial and error are a fun part of it. If you make a beer that in your opinion tastes like three day old socks, RDWHAHB. Trust me, you'll find a friend that loves it.
Don't get bogged down by complicated brewing techniques. Keep it simple, and grow at your own pace.
Extract beers and kits are good. I still use extracts on a lot of beers. Go to partial mash and/or all grain when you are ready. Or stay with extracts if you wish. It's all good.
Pick a supplier that is a homebrew supplier as their main business. They should have the knowledge to help and advise you. I've seen too many that are set up in a corner of store, with clerks that have never brewed.
Brewing software is great, but you should learn why the calculations take place. I still start all of my recipes with a pencil and a piece of paper. But then again, when I first started, we didn't have home computers.
Document your brewing sessions. And note any and all changes from the recipe. Some of my best beers started out as "oops...".
Learn to enjoy beer. Cook with it. Use different glasses and notice the change in perception. Try a variety of styles with a wide range of food.
But have fun. RDWHAHB. And, in case I forgot to mention it, clean and sanitize. Always.