I have noticed that practice putting inside messes me up more than it helps. I especially experienced this over the winter. Putting in my warm, flat, open basement was so different from the cold, windy, possibly wooded course that it didn't help me. I would say try to practice outside rather than inside.
Also, move around the basket. It seems like it shouldn't matter because theoretically all angles at a round basket are the same but moving around will give differing surfaces that you are putting from and different angles in relation to the wind.
Also, watch videos of pros. The Feldberg putting clinic posted above helped me as well as watching the Paul McBeth putting video where he putts from different distances helped me out too.
Hope that helps.
I have to disagree with the bolded....at least most of it.
Obviously, if we all lived in FL or CA, we would practice outdoors in varying wind all year long....but I'm not so lucky.
At the end of last fall, my putting was horrid. ~50% from 20'. Dumb luck from 30'.....without wind. I had no confidence, no muscle memory, no consistency. 1/2 the time I missed - I had no idea why.
I have just barely 10m of room in my basement and a practice basket and live in NY....so its a long winter. I did play a round a week for winter league, but that was it. No field work, no casual rounds for months. What I did do, though, was practice a TON in my basement (thank you JYLY putting game). Throughout the winter I was getting better and better in my basement. Averages were going up, confidence was going up. It didn't translate well to the course though....bad footing, layers, etc.
In my basement, though, by spring I was at ~90% from 20'. 60% from 10m. Huge improvement. The biggest thing that stood out to me was that I now have developed strong muscle memory and a consistent putt. Now if I miss, I immediately know why (usually chicken out and short arm it). Now if I do that...I can fix it.
With all of this clicking and finally losing the layers, I noticed something magical this spring when outside. Sure, it was rough at first dealing with wind...but now that I have a consistent putt I can actually make a meaningful adjustment to the wind. Granted, I'm not hitting 60% from 10m like I did in my basement....but I'm not completely shocked when I drain one, either.
My point in all of this is that putting in that perfect setting has its uses. I think it actually helped me progress faster as it removed variables and allowed me to focus on building that muscle memory faster than if I had spread that practice out over varying conditions. Of course it also helped that it is much more fun to practice in a t shirt during the winter than freezing...so i got more time in as well.
Now that I have that muscle memory, its time to maintain it and build experience with adjusting that baseline motion to a variety of settings & wind conditions to take my putting to the next level.