You can often find sewing classes offered through fabric stores or sewing machine stores - try seeing what your local fabric store might have to offer. Also a lot of information can be found online for weird little fiddly stuff, like what kind of needle to use on what kind of fabric and suchlike (sometimes your sewing machine manual will have some of this too). I'm actually almost completely self-taught but I don't recommend this method - it takes a lot longer to do something the wrong way a few times before you learn a way that works!
Sewing machines - some of these I've used, some of this is just what I learned through research. Even if you decide on a brand, try out a bunch of different machines in the store - don't buy something if you "test drive" it and it makes you feel uncomfortable in some way to use it (like it shakes too much, or just feels weird somehow). A sewing machine will last you a really long time if you're happy with it and you take care of it.
Also think about what you want to do with it. You probably won't need a lot of fancy decorative stitches, but you probably will want something that will be sturdy and can sew through a lot of different types of fabric without throwing fits.
Singer: Old machines are excellent, I've heard new ones suck. Singer got bought or something and the quality went way downhill.
Kenmore: Sometimes these are great and sometimes they're terrible - I hear it's because the manufacturing rotates so it's different every year. Can't say for sure, but the one Kenmore I've had experience with was fine. (White supposedly has the same issues but I have never tried a White machine.)
Babylock: Solid, reliable brand. I have one of their sergers and I LOVE IT.
Elna: I love my Elna (my first machine and I still use it often) but they got bought so I don't know if you can find them anymore. :/
Pfaff: Never used one of these but I hear very good things about them.
Viking: Viking = awesome. They can be expensive though.
Janome, Brother and Bernina: I know nothing about any of these, sadly.
Sewing is a great skill to have. When you can make exactly what you want instead of trying to scrounge for something that looks mostly right, it's very satisfying. And sewing is useful for more than just costumes, of course - you can repair clothing if it gets holes in it or something too once you know how...