Post the blend, but it is possible to get hair that is identical in particle edit, object and rendered views.
Blender hair definitely needs a lot of work to be more intuitive and easy to use, and there’s plans to redesign the system/workflow completely but until then here’s some things that have made the work easier for me, I hope they make the work a bit easier for you too:
- Always use a scalp mesh instead of creating the particle system on the same model. If you’re working on a character that has several modifiers it gets increasily diffcult/slow to edit and it’s very easy to mess up the modifier order, resulting in hair that looks completely different in viewport vs render.
- The particle system modifier should ALWAYS be before subdiv, this way you can be sure that even if the subdiv levels are different for viewport/render the hair will stay just as you set it up in the viewport.
- In the particle tab properties, make sure that you always have the render and viewport display steps the same, and in the case of long hair, check the B-Spline option.
- Use Interpolated children, they better follow the hair guides and simple children tend to separate too much from the mesh and appear like floating in mid-air in some cases.
- If working with real scale values, I find a diameter root of 0.05m and a tip of 0.01m for the Hair Shape look best in render, but it may need a bit more children hairs and increases render time though.
- If you’re going to render the hair relatively close to the cam then in the Scene Hair settings change the shape from Rounded Ribbons to 3D curves, it also adds a bit to the render times but it looks much better.
- When it comes to styling and grooming, consider using different particle systems for different sections, for example: a main particle system for the bulk of the hair, another one for flyaway hairs, one more for sideburns and another one for the main curls; this way is easier to achieve specific looks and also helps with the performance in the viewport.
This course is outdated for shading and rendering but still holds up when it comes to the styling and grooming, still the best I’ve seen out there:
Styling and Shading Realistic Hair - CG Cookie
Styling and Rendering Realistic Hair with Blender and Cycles Pt. 1 - YouTube
Excellent stuff, thank you all!
The Aneesh tutorials are some of the best out there when it comes to hair. I’d forgotten a lot of the concepts and parameters.
Well, I’m not sure if anyone has mentioned it but since we’re on the subject…
You be careful with “Steps” settings. The higher “Steps” value, the more BVH build time, higher RAM usage, and heavier Viewport performance.
I haven’t used this but it looks useful.
Well this kind of did it… 
I have no idea why this is happening. Any ideas?
I took the advice and after creating the hair system I proceeded to erase all of the particles and started adding them one by one, grooming them and giving them shape.
After adding a few particles I pressed interpolated children just to have a preview of what I was doing and this came out.
There are no weight paint issues or any unwanted faces selected.
Can you share the file? That doesn’t look right… 
There is a good chance that you already know that, but:
I think the modifier stack might be messed up.
Maybe your hair particle system is situated before the Armature Modifier… it should be Armature Modifier first and then the Particle System. The other thing could be that you are trying to edit a particle system with a baked Hair Dynamics… it should be disabled or cleared before editing.
Thanks but there are no modifiers I converted them all to mesh before going ahead with the hair system.
As for hair dynamics, nothing of the sort unfortunately
How can I share the file? Do I just upload it here?
You can share files up to 5MB here on the forum (you use the Upload button). Or you can upload .blend file up to 24MB here:
When it finishes uploading, you share the new website link here.
Thanks for the link. My blend project file is 450MB. I´ll have to find another way.
One thing I`ve noticed is that those hair anomalies dissapear as I decrease the number of path steps of the hair particles on the tool tab
Maybe separate just the head mesh in a new file without textures and share just that?
I could do that.
Today I re erased all that I did yesterday and started from zero. With all of the info gathered from this thread I got to get some better results.
Still found that anomaly (which had also occured to me in previous projects) around the ears (children piercing through the ear) although there were no particles nearby. Solved it by setting the weight paint to zero around that area.
I guess as soon as I start setting up the flyby hairs there´s a chance the problem will show up again.
Just in case, you understood what I had written before, right?
Yes. Scale shows up perfectly, thanks!
Looking at the images again, it seems to me that you’re maybe using one of the Kink types too?
If that’s the case maybe try to reduce the Amplitude value, the default values (like most of the defaults in Blender 
) are way too high for work with hair at a real world scale.
I hear you. Interestingly I had no kink style at that point as it was a test just to see how the children were aligning.
Maybe it’s got to do with the size of the model. That head is around 9mts big
Then that error is even weirder 
Most of the issues I’ve had with hair in Blender come from using models that are very small… Though 9mts is too big, is there a reason to work with such a huge model?
Anyway, if you can share a simpler version of the file I’d like to take a look at it