I always used tar, i found that zoo pads were the best with tar. Pads designed for a grind don't work too well with tar and smooth rims. You really want a decent working brake before you put the tar on. The problem with tar is people slap loads on, and then complain at how bad it is, tell everyone else how bad it is and it gets a bad rep. How tar works varies on what the weather is doing. If it humid and cold it doesn't work too well. It works terrible in the rain too, in fact it probably makes the brake worse in the rain than having no tar at all. When hot, you need to put very very little tar on. I found that applying small lines towards the center of the wheel is most definitely the best way (tire towards the spokes / width of the rim) as this way covers the rim evenly as it spreads when you brake. Applying it along the rim is the worst thing you can do as it spread ontop of it's self and this leads to poor braking, pads sticking and lack of teeth in your mouth. So to sum up: You need good soft pads, zoo or something similar. When it's hot, put much much less on, remember you can add more but can't take it off. Apply small lines perpendicular to the rim.