Help With Lineart & Drawing Tablets?

Hello, I’m an aspiring artist. I love drawing it is one of my favorite hobbies but everytime I scan it on the computer andl lineart my drawing using a marker the lineart look disgusting and sloppy. I see other artists with such neat and thin lines, how do they do this? And is it possible to do such neat and thin lines with out a tablet or drawing pad? And also is having a drawing tablet the only way to get neat and clean lines in your lineart and do you think it is really necessary to become an artist? Also if you have a tablet how long did it take you to get one and also is it easy to use and draw with?
The only editing program I have is Corel PSP X2, I tried using the pen tool but it ends up looking sloppy and not like the way I drew it. Help?!?!