+1 on the 'practice amp' scourge. There's a lot of junk out there, and a bad sounding amp can hinder your progress.
Craigslist has a ton of used stuff at great prices. Is there a college near you? Wait until the end of the school year/semester and check. There's usually a bunch of stuff being sold off. Pawn shops can have some gems too (although rarer these days). Just don't buy anything new just yet - unless it's an SX.... You'll get more value in a used bass and amp.
It's always a good idea to have a teacher if you have the funds or there are local community college/school lessons available - even if only for theory. However, if it's not practical for you don't be discouraged.
Wavy lines......back in my day..........
Actually, the main point would be to use your ears. That's what will make you a great bass player. It's not what you play, it's what you leave out. Learn how to tune by ear.
There was a time before the interweb when we bass players would ruin records (they were big black plastic things....hehehehe) by skipping the stylus back to the chorus again and again to get the part down. Books were few and far between for bass....
That 'skill' enabled me to really hear the bass part on any song. It helped me to feel/hear the difference between a 'B' played on the 'A' string, or on the 'E' string (there's a sonic difference, a different feel). I helped me to really understand the song structure, and to see the merit of the notes bridging two separate song sections. You'll be thoroughly surprised at how the bass line runs on some of the classics. I bet there will be a few that are totally different to what you expected.
Try to learn how to read music, or at least TAB. Modern Bass and Guitar magazines will have transcriptions of songs with bass lines. Playing along will help you get the feel of things.
Also, familiarity with the instrument is paramount. You don't need the amp, just have the bass on your lap as you watch TV or such. You'll hear and feel the difference from playing over the neck, over the pickup, at the bridge. Get to know what it feels like in your hands. Watch people playing and work out what they are doing. It may not make sense immediately, but it's easier to just try it immediately than to try to remember it later when you eventually pick up the bass. Another on is to watch a guitar player play a chord, and play the notes of that chord individually. It teaches more than just sound and scales. It also will make your fretting hand naturally move to the next note. Newbies can be all fingers as they are yet to discover the ergonomics of economy of movement.
There are some great interweb video tutorials, and some great videos of great bass players. Listen to all of them. Try some of your favourite songs (and yes, the WHOLE song). It's more osmosis than instinctive.
Play until your fingertips hurt. Play some more. Always be listening.
Lessons are a great idea, but not everyone has access.
Go to gigs and make friends with the bass players. They love talking shop.
Maybe one of them with give you advice, lessons. We're a relatively rare breed, so we aren't as territorial as guitar players.
Above all have fun, and enjoy it. You probably will obsess on it for a while, but we all did [I see you all out there whistling and trying to look cool and nonchalant!].
You'll find your groove soon enough. Just don't be discouraged because you chose 'Teen Town' to start off with! Baby steps. Immerse yourself in the world of bass. Every genre, every style, every type of bass. Try a pick, try fingers, thumbs, tapping, slapping. The sound in your head will find its way out naturally. Obviously there are some habits that can actually hurt you (poor hand positioning etc.), but sometimes there are some amazing sounds come out of unorthodox approaches. Nobody can teach you that! That comes from within.
When you're not noodling on the couch and actually practicing use a strap and stand up. The strap should be set at the optimum length for your playing - i.e. where it is most comfortable. If that means that the top horn is up your nose, so be it. I'll wager that a bass around your knees isn't as comfortable as it could be... It may look cool, but it won't help your playing.
