best tips for beginners; start with a slackline kit, or if you're really short on money; tubular webbing and a ratchet ^^like above ...
(the technique with the carabiners works fine but is quite complex and very hard to setup on your own, especially if you haven't done i before and are not sure you're doing it correct....)
technique tips for beginners;
1) look at a fixed point, preferably the anchor point you're walking towards or the horizon....
1.2) don't look down, its harder to estimate distance/position:balance if you cant see the horizon ...
2) bend your knees, lower your center of gravity
3) still having trouble; have someone sit down in the middle of the line, this works as a shockabsorber and makes the line much more stable
4) try to place your feet parallel on the line, in the beginning this is quite difficult, and if you don't feel it; try stating with placing your feet under a sharp angle..
4.1) in the beginning placing your feet perpendicular to the line is gonna make you rotate sideways and lose balance.. once you're a bit more experinced you can experiment with this and learn how to turn around on the line ...
5) with your first steps it is ok to hold someones hand, this gives you a good feeling of how the line reacts
5.1) you can then proceed with holding only by a finger or ask them to stand behind you and gently pull your shirt up around the back of your neck, this gives you a little bit more stability but still allows you to have that completely "free" feeling....
any more questions/problems, pm me, i'm not an expert but as long as you aren't either i might be able to help you out!
grtz!
-fred