For starters, do what you can to stop using ruled paper as it degrades the quality of your drawings.
Because no matter how good you are or become, your art will never look as good as it possibly can if you use ruled paper.
And you don’t need to get expensive drawing paper either, unless you’re going to do drawings on a professional level.
Simple printer paper will do just fine for practicing and it’s usually only a few dollars per ream, ($4.50 USD for 500 sheets where I live).
Next, I'd suggest giving this website a thorough read through:
http://hippie.nu/~unicorn/tutAnd as far as software…
Some drawing programs to check out are
Gimp,
MyPaint and
Krita (And here's some Wikipedia info for
Gimp,
MyPaint and
Krita).
(All of those are Free and open source.)
Another program is
ArtRage (
wiki info on that), it’s a very neat program as it simulates realistic drawing and painting, (for example, the brushes can actually get dirty from use if you want them to).
The only downside is that this one is only free for the “Starter Edition”, and that version does not have layer support, and a couple of special brushes are not available.
And in regards to techniques…
Most of my focus leans towards digital methods, so in that case, just remember that layers and opacity settings are your friends.
Don’t be afraid of having too many layers, (most of my projects usually have well over 50 layers and some as many as 200).
So if you’re ever in doubt about something, do it on a different layer so you don’t mess up the things you want to keep.
Also, with the exception of things that need to be combined, try to keep separate colors on separate layers, as it can help make things easier to work with.
The other thing is to make good use of opacity settings, especially for brushes.
When you don’t need a hard line, try drawing with a low brush opacity, (somewhere between 0.1% and 10.0% depending on the program), as it can help add nice gradient transitions, and works nicely for shading and shadows.
I can't add nearly as much advice for physical media as I can for digital so I hope that was helpful, …and beyond all of that, all I can say is practice.