(Multi) Countjump help

Hey I got some problems while practice Countjumps.

First is I can barely hit the edge. Most time I have like ~15 units jumpoff or more. Its annoying because I need this "free space" to prestrafe and duck.

the next problem is that I lost my prestrafe (speed) after a second duck or more. After my first duck I have like ~281 pre and second only 240 or less and when I jump after the duck even less.

(notice I mean not these 180 degree countjump)

Would be nice if someone could record a bit longer demo of doing double-, multi-, countjumps on a lj block or some multicountjumps offblock.

and oh, Yes I know practice is important to get better but practice the wrong techniqe is worst ;)

I hope someone understand what I try to ask and sry for my english ^^

Ihave the same problem , can someone help me