Pay attention. Lapses in attention make sloppy projects and can easily lead to a serious accident.
I commented some days ago about safety practices and today I'm taking the time to read responses from others. The theme of safety keeps popping up and I thought that I'd make a couple more remarks. Lots of folks say to be safe but let me expand simply never work tired, hurried, or impaired by alcohol or drugs (Rx or otherwise). That's when accidents happen, or at least, mistakes. It only takes a split second to ruin a piece of a project, or larger, particularly using power tools. This is supposed to be rewarding and fun. Things take a lot more time than you anticipate, but don't push it. Know when to walk back to the house or change the scenery.
Another common entry has been "start small; you don't need a shop full of tools starting out". You really only "need" measuring tools, a saw (hand or table) to cut pieces to size and then fasteners for whatever method you choose for that project. Examine your history and evaluate if this is a hobby that you'll stick with before spending money. I agree with this, to this extent. If you come across a great buyout deal, particularly from a "hobby shop" make the deal happen if you know you are getting decent stuff. That involves some research ahead of time on your part. I built my home 35 yrs ago with a table saw, a circular saw, a framing square, a combination square and a radial arm saw that made things easier but was not necessary. Additionally, there were hammers, levels, tool belt, etc., more carpentry essentials. When it was time to build cabinets, I bought a couple routers and a dado blade. I've replaced the original tools and added other stationary power tools by patiently shopping for good used equipment and did not spend more than 50% of retail for most of it. If you plan on using sheet goods, you'll need a good circular saw to break down 4x8 sheets in a hobby shop. With lots of space and help around you can set up a table saw but most of us cannot dedicate the shop space required to handle sheet goods.
Like others have said, start with cabinetry for the shop so you can learn the basics and make a few errors without having to throw away much. I paint most of my shop tables and cabinets to reduce the finishing time. Finishing is another animal that can be conquered later.
My last repeat of other advice is to be sure of the operation you are performing during each and every step. The devil's in the details. What side of the line do I cut on? mark the waste side with an X! Envision the operation - if the piece you want is a small piece cut from a larger one, where will it land when cut? Make sure it is supported and captured without being dented from a fall or splintered by the saw. I usually take the time to cut the outer layer of plywood with a sharp utility blade, cutting along the pencil line, sometimes cutting two pencil lines to allow for the saw blade thickness.
In summary, there's a lot to learn about each step so read all you can and be very patient. There are rewards along the way as you accumulate knowledge, but it all takes time.