While the double bass has some differences to the violin, it is still a violin and a rightful member of the violin family because it is internally constructed identically to a violin. It's tuned in 4ths instead of 5ths like a violin but that's because you couldn't finger a bass in 5ths for the most part although Red Mitchell actually did--don't ask me how. It should be noted that the cello was originally called the bass violin but lost the title to the double bass.

As far accessories for your bass, go to Lemur Music. Don't have the link offhand but just type it into your browser. That is where professional bassists go to get stuff. You can get pickups, amps, strings, cases, quivers, bows--whatever. In fact, if you have factory-installed strings on your bass right now--change them! Don't wait, there's no point to it. I ordered D'Addario Helicore medium tension hybrid steel strings for mine and I love them. The type of string depends on your playing style. Some are made for bowing, some are made for plucking. Hybrids are made to do both. Weed-whackers have a lot of stretch and are made for slapping although I slap pretty well with mine. I don't recommend gut strings but some guys only use gut. I recommend steel strings.

When changing strings, do them one at a time and tune it to the right pitch before changing the next string to maintain proper string tension. Failure to do this may cause the soundpost to fall over. The soundpost is essential to the sound of the bass but is held in only by string tension. If it falls over, you'll have to find a luthier to put it back. You can do it yourself if you know what you're doing.

Check your string height. Hope you have an adjustable bridge with the little wheels on them. You don't want the strings buzzing against the fingerboard. They should be a good half-inch above the end of the fingerboard.

As far as websites for intruction--forget it. Don't use Expert Village. It's funny to go to these clips and read the comments because everybody is so pissed off at the instructors but if you're going to those clips for instruction, you'll never learn anything anyway. Those commentors are NEVER going learn the bass that way and if they had an instructor they wouldn't go to those clips because there's no need. You have to get a teacher. You'll NEVER learn this instrument on your own. It has so many secrets that only someone who has mastered it can teach them to you. Especially using the bow. I can bow reasonably well now but could never have learned it without an instructor.

The neck is divided into positions and you really need an instructor to teach them to you. It is virtually impossible to learn them on your own unless you have a tremendous natural aptitude for an exceedingly difficult instrument (you bought it so you may as well know it is not going to be an easy journey). You have to know your major and minor scales and memorize the note names because when you start walking the bass, you can't do it without knowing the note names in every position in every key. When you hear some jazz guy walking that bass and you wonder how he can just go on and on never doing the same thing twice and yet holding everything together, he knows what notes he's going to play before he plays them. Even improvising, you have to know the notes you're going to use or you're just meandering around puttering off random notes that sounds completely amateurish.

You have to learn to SIGHT READ very well. If you play this instrument and don't know how to sight read or how to bow, you're wasting your time. And once you get to learn your way around the fingerboard above the body, you have to learn the thumb positions playing high up that fingerboard because all the fingering techniques to employ above the body don't work below the body. You have to switch to thumb positions. Eventually, you'll have to learn how to go back and forth between the two fingering styles seamlessly.

As for books, when you get a good instructor, he'll tall you what books to get. Your basic book, though, should be "New Methods of the Double Bass" by Franz Simandl. It is the bass-player's bible. If you're not learning from that, I would question the quality of the instruction. If all you want to do is keep time on the bass, you wasted your money. It's an expensive time-keeper. If you invest in one, learn it right. It takes dedication and lots of practive--every single day. Every. Single. Day.

Finally, I hope you laid out some decent coin for this thing and didn't buy some cheap-ass $600 piece of junk off the internet. A decent double bass is going to cost in the $2000-$3000 range just for a good student bass. A pro model is upwards of $4000. I've seen them for $20,000.

Just the wood costs more than $600. It has to be the right wood, properly cured, seasoned and sawn and it has to be cut and shaped by a master. There's no way an $800 bass could be worth a crap. A good luthier wouldn't waste his time constructing a piece of junk so the workmanship is going to be garbage. It may look alright and sound alright but soon it will start to tell on you, e.g. it will start to come apart, start pull out of shape, refuse to stay in tune, etc. Also, it has no resale value. No reputable music dealer would buy it from you because it's junk.

But look at it this way: a decent student bass costs no more (and often less) than a good Martin guitar.