Before you make any purchase, you need to ensure that you are aware of all safety procedures and any restrictions on your licence.
For example, if you are a learner then you will not be able to carry a passenger but it is best to look into all possible restrictions on what you can and cannot do. Your type of licence can also have a certain maximum engine size so make sure you know all details prior to any purchase.
You also need to speak with your insurance company and check how much your monthly premium will be for a possible bike because if it is more than you can afford then it may be impossible as it will be a more powerful dirt bike and unlikely one a first time owner can handle. Search the market properly and test which engine power you can handle without any risk.