Before I started to sell.. I did more than 75 free sigs. Practice is the key and I guarantee you that if you do something like me :
1.You ll make people happy
2.You will have sooo much practice and you will be 100x better
3.People will know you
Dont start selling too early cause if you do, you will not have lots of customers and you will stop practicing.. :/
I find that having "real customers/persons" ordering for a free sig is way more of a practice than trying to practice by yourself. Also, Since its free, people wont be too hard with you
you can see my progress/the way I did it on my thread :
http://www.sythe.org/graphics-marke...rill-reopening-future-graphics-order-now.html
Just scroll/change pages and click on the links. I edited lot of orders completed to just links when I opened my shop
Thats the second free sig I did: (i edited the first post on my thread so dont know wheres the first one)

last sig I did before I started to sell:

See that progress?? Man it helps, trust me.. I learned SOOO much doing this
If you do the free service during a long time, these are my advices:
1. Edit your thread each time you did an order and put it there. You will see your progress from your first one to the last one. I did it and it was awesome
2. Try new things. Its free so why not? You will learn some new tricks while doing this. Dont use the same effect all the time.
3. Talk with the customer, try to do a form like I did. Based on the information he provided you, you will have to be creative and do a sig with it! Thats good practice.
4. When you see LOOOOT people are coming to you for graphics and you have 9 orders per day.. (lol) + you think you are ready. Open your shop , starting cheap
I also recommend photoshop. GIMP is very limited and you will see that when you re more experienced. I started with GIMP and changed to photoshop right away. Dont worry, for the things you are doing, its practically the same thing in photoshop. Photoshop CS2 is Free from Adobe's website and I did graphics in it for months before changing to Photoshop CC
Man... I got SOOO MUCH BETTER doing this and now, after 2 years.. here I am with an irl graphics design business. THANKS SYTHE
first graphic ever :
Now: