You're doing Continental knitting, holding the yarn in your left hand. It is faster and, contrary to the commenter's assertion above, it's LOOSER than English (right-handed) knitting, which is why you're overcompensating with the pulling tight. (If you're a right-hander you may find it easier to hold the yarn in the right hand to get an even tension. There are videos of both styles here.)
Even tension is controlled by how you wind the yarn around the fingers of your hand as you hold it. There are all different ways to do it, and I experimented with a couple before discovering that wrapping it once around my two middle fingers was the easiest for me. I've also seen wraps around the pinky and index, woven between all the fingers, and slung around the back of the neck (with the yarn on your right, coming over your right shoulder, around the back of the neck, and feeding into your left hand from over your left shoulder.) Experiment and see what feels best for you.
Once you wrap the yarn, don't pull it tight. Knitting the next stitch will do that. I used to pull it tight twice: once when I wrapped the yarn, and once when I knit the next stitch. After a few rows I could barely get the needle in. I had to learn to knit a little bit more relaxed, as well, to counteract my tightening ways.
Slipping stitches at the beginning of the row -- You might try slipping as if to knit: put your needle in left to right and slip it off the needle. That'll twist the stitch and make it tighter. Alternatively you could just forget about the slipping and try knitting the stitch and pulling it extra tight.
I concur with those above that you're probably adding stitches at the beginning of a row by letting the thread come over the needle, or, if you're knitting and purling, by moving the yarn over the needles when switching from front to back, instead of between the needles. I had the added-stitches problem like mad on my first scarf. Once you've practiced a little and your knitting gets more consistent and mechanical, you'll stop doing that. Ditto with the getting the needle in the right hole and the sticking the needle through the yarn. I still do that sometimes, it's just something you have to watch for.
As for the fact that knit happens behind the needle and is hard to see: When you stick the right needle in the loop, it should open it enough to see through. Your left middle finger should be perched on that stitch, holding it in place on the needle and letting you stretch it open, and when your index finger moves the yarn into position the middle finger stops it right at the stitch opening. Then the right needle can scoop that little sucker up and through the loop.
It may also make it easier to hold the left needle so that the tip is pointing to 1 or 2 o'clock (where 12 is straight up).
Just FYI about crocheting: I hear that it is easier, but it just looks too loosey-goosey freestyle to me. I like having all my stitches lined up on a needle where I can keep track of them, rather than crochet willy-nilly into any hole that looks available. But that's me. (And my god that sounded a bit dirty.)
The nicest patterns I've seen for crochet are toys and bags. It's not very well suited to clothing, because it makes a thick and somewhat inflexible fabric (it uses three times as much yarn as knitting for a fabric the same size). I also don't like the blocky look of the stitches, but that's a personal taste thing. However, if the seventies kitsch factor appeals, go for it!
Finally, be patient. The first thing you ever knit is going to suck, guaranteed, end of story. But by the time you finish it you'll have developed the skillz to do a nice job on the next thing you tackle. Even then, I still sometimes have to start over several times when I'm knitting something new. So use it as an opportunity to examine your technique and tailor it to something that works best for you.
no subject
Even tension is controlled by how you wind the yarn around the fingers of your hand as you hold it. There are all different ways to do it, and I experimented with a couple before discovering that wrapping it once around my two middle fingers was the easiest for me. I've also seen wraps around the pinky and index, woven between all the fingers, and slung around the back of the neck (with the yarn on your right, coming over your right shoulder, around the back of the neck, and feeding into your left hand from over your left shoulder.) Experiment and see what feels best for you.
Once you wrap the yarn, don't pull it tight. Knitting the next stitch will do that. I used to pull it tight twice: once when I wrapped the yarn, and once when I knit the next stitch. After a few rows I could barely get the needle in. I had to learn to knit a little bit more relaxed, as well, to counteract my tightening ways.
Slipping stitches at the beginning of the row -- You might try slipping as if to knit: put your needle in left to right and slip it off the needle. That'll twist the stitch and make it tighter. Alternatively you could just forget about the slipping and try knitting the stitch and pulling it extra tight.
I concur with those above that you're probably adding stitches at the beginning of a row by letting the thread come over the needle, or, if you're knitting and purling, by moving the yarn over the needles when switching from front to back, instead of between the needles. I had the added-stitches problem like mad on my first scarf. Once you've practiced a little and your knitting gets more consistent and mechanical, you'll stop doing that. Ditto with the getting the needle in the right hole and the sticking the needle through the yarn. I still do that sometimes, it's just something you have to watch for.
As for the fact that knit happens behind the needle and is hard to see: When you stick the right needle in the loop, it should open it enough to see through. Your left middle finger should be perched on that stitch, holding it in place on the needle and letting you stretch it open, and when your index finger moves the yarn into position the middle finger stops it right at the stitch opening. Then the right needle can scoop that little sucker up and through the loop.
It may also make it easier to hold the left needle so that the tip is pointing to 1 or 2 o'clock (where 12 is straight up).
Just FYI about crocheting: I hear that it is easier, but it just looks too loosey-goosey freestyle to me. I like having all my stitches lined up on a needle where I can keep track of them, rather than crochet willy-nilly into any hole that looks available. But that's me. (And my god that sounded a bit dirty.)
The nicest patterns I've seen for crochet are toys and bags. It's not very well suited to clothing, because it makes a thick and somewhat inflexible fabric (it uses three times as much yarn as knitting for a fabric the same size). I also don't like the blocky look of the stitches, but that's a personal taste thing. However, if the seventies kitsch factor appeals, go for it!
Finally, be patient. The first thing you ever knit is going to suck, guaranteed, end of story. But by the time you finish it you'll have developed the skillz to do a nice job on the next thing you tackle. Even then, I still sometimes have to start over several times when I'm knitting something new. So use it as an opportunity to examine your technique and tailor it to something that works best for you.