In addition to getting a hydrometer, be aware of the recommended temperature range for the yeasts that are used in your recipies . Yeast is alive, and produces its own heat, and so the temperature of your fermenting beer can be several degrees higher than room temperature.
One of the more common mistakes is to ferment with a yeast that wants low 60s in a mid-70s room, which can add nasty paint thiner flavor to the beer. The two most overlooked ingredients in every food recipe are time and temperature. That’s like 10 time truer for beer.
Most important: Allow yourself to screw-up. Your first batch will likely not be “pub quality” but your brewing will improve over several batches. You learn as much from your actual brewing as from reading. The most disappointing thing I’ve heard from someone when trying to push homebrewing is “I tried it once, and didn’t like how it turned out; it’s easier to just buy.” Again with the food analogy: you don’t wake up and be a master chef, it takes practice.
As others have said, welcome! This forum is probably the most troll-free zone on the Internet, so don’t be afraid to ask “stupid questions” you may get conflicting answers to your questions, but that’s part of the fun too...