I would suggest finding a method that works for you by practicing. It does get easier.
When I finish a needle I move the stitches to the middle of the needle this keeps them from sliding off.
Needle tip protectors will also keep the stitches from coming off the ends. Longer double pointed needles will also make it less cumbersome. If I have
a lot of stitches I use a circular needle. Socks and sleeves I use double pointed needles as there are less stitches on the needles. There is also the magic loop for knitting in the round; I
have watched some tutorials, but I've not tried it yet.
If you are insistent on using double points, I would suggest putting either rubber bands or point protectors on those needles you are not using. That will keep your stitches on your needles. When moving from one to the next needle, make sure you tighten your wool between the two needles. Your stitches should even out when you block your work. I always had trouble with double points and this helped me, but when I moved over to magic loop, no more problems. I use magic loop for everything now instead of double points.