The best thing to do when you are a beginner is to first make sure you have an idea what you will do. You can do some research first about what you want to do and which among the cryptocurrency you think is best to invest with. Once you are already sure where you want to invest, create your own etherwallet and put sufficient amount for gas or transaction fee. Then, you can go to the different trading sites on where you can buy your desired coin. You can monitor its price on the web too so that you can see if its value changes. Buy when the price is low and sell when it is high.