NEVER ever try to count "dots" and "dashes". Start by learning several characters per day. It's best to group them like - E and T, I and M, O and S, L and F, 1 and 9 and so on. Don't learn it by following the alphabetical sequence. Get the idea?
Set overall character speed at 15-20 WPM but have a long pause between the characters. Every day, add a few new characters or numbers and repeat the all previously learned ones.
Once you get a solid copy of all numbers and letters, add a few common characters like - "?", "/" "space". You won;t need to know them all, just the common ones.
So, once you know that, begin to listen to live QSOs and slowly begin learning to transmit. Again, don't get too slow. Longer pause is ok. Then practice, practice and practice more.
Don't be afraid to make mistakes. Learning CW is kind of like learning a simplified foreign language. At first you can't even distinguish words but with practice, everything starts making sense. It just takes time and dedication, don't get discouraged at first. It will come to you. Next thing you know, you'll be a net control station for the Arfcom CW net.
A 300 Hz mechanical filter in your FT-857d will make a tremendous difference. I could not believe how effective that filter was. In my opinion, it's worth every penny. A 2.4 kHz SSB filter is nice too but it's not as noticeable as the 300 Hz, CW filter. You won't regret it.