Don't neglect sanding your wood. Sanding may be tedious, but the quality of your workmanship will suffer if you leave the scrapes and nicks where they are. Not to mention, those scratches and nicks absorb more stain and paint, making them stand out more, and making your work look shoddy.
Sign up for a woodworking or shop class at a local school. You can definitely teach yourself a lot about woodworking, but there's nothing better than learning from a professional. You'll pick up important skills much more quickly, and you'll make a lot of great friends along the way.
All woodworking shops should have stair gauges. They are generally used for laying out stair jacks, but they can be used to clamp carpenter's squares. This will make the carpenter square into a circular saw guide. You can have straight cuts every single time when you use that square.
Use some affordable filters for collecting fine dust. The filters and micro-filtering bags made to catch this dust can get pricy after several replacements. Try using the ones that are sold for use in household vacuums.
You can buy the cheap ones and easily modify them to fit your shop vacuum. Cut off the top a bit past the small opening. Turn the whole thing inside out so that airflow still flows in the usual direction. Slip it over your foam filter using the retaining ring to keep it in place.