In order to learn to graffiti you need to know that it's about more than just learning how to tag your name. To avoid making a bad name for yourself or getting on the wrong side of other graffiti writers you've got to be committed to learn to graffiti the right way.
All graffiti writers start out labeled as 'toys'. To lose that label you need to work to earn the respect of other writers as well as show respect for the meanings and history of graffiti. You will never lose the 'toy' label if you do not learn to graffiti showing respect to other writers and graffiti history.
The 'toy' label can also change to mean an unskilled writer or one that is disrespectful of other writers work. If a graffiti writer doesn't bother to learn to graffiti with any kind of distinctive style or technique they will be labeled as a toy. These writers are most likely only after the fame, glory and recognition other graffiti writers receive, but they don't want to put in the effort or try to develop their skills to earn it.
When starting out graffiti writing is generally tag. Writers learn to graffiti by tagging using markers, spray paint or any other writing tool. Because of this tagging is often referred to as the root of graffiti. In order to be a skilled writer you must first become proficient in your tag first.
When you've decided on your tag name practice writing it. While you are just starting to learn to graffiti it's a good idea to practice in the privacy of your home on scrap paper or any other kind of found objects. Any public work you do should only happen after you've developed your own unique style and name and when you have a good understanding of how other graffiti writers operate in your area.
Style is hugely important when you are starting to learn to graffiti. You not only have to develop your own unique style but you also need to show skill and technique in order to gain the respect of other writers. As mentioned before graffiti writing without style is just tag - tag is done by toys.
Style is not necessarily just about your tag or the design of your pieces, it is also about being able to get high quality graffiti up in obscure and often difficult locations. The more difficult and obscure locations your graffiti is seen in, the more respect you'll earn. Even quick throw ups need to demonstrate some kind of unique style in order to become recognized and respected.