For altering your own avatar, you will always need a special tool called "Pose Stand".
This Pose Stand allows you to place the prims correctly on the avatar's body.
You can build your own Pose Stand very easily.

Create a table and chairs in Second Life, decorating your home.
Building furniture for your home, table and chairs are specifically designed for novice and in a very modern style.
You are passionate about interior design, furniture, interior design.
Here's a little article that will be really useful.
You can find tips and textures in this tutorial

Building a small pink very decorative clock for your living room, hand-painted motifs and embossed designs with a kitten in sculpty on the top.

To build things you need multiple prims. 
How to join two prims together to form a single object.

Here's how to make hair prims which seem the most realistic.
The texture structure of your hair is very important, but the most important is the location of prims.

To build your first hair lock, rez a torus on the ground

The balloon is made of two kinds of prim: several spheres and a cylinder