This is an excellent question, and every cryptocurrency buyer should be aware of it. Before trading any cryptocurrency, you should have enough savings because their costs are very high. Then you need to set the limits for profits and losses. It means how much profit and loss you can bear with your investment.
Similarly, you should buy and sell bitcoin at trusted platforms if you are proceeding online. No doubt, there are distinct bitcoin dealers who deal in both selling and purchasing bitcoins and other cryptocurrencies and this Australia based bitcoin deal
https://bitcoindealers.com.au/ is one of them. Actually, their rates and quick services impressed me a lot and probably, I would like to buy cryptocurrencies from this dealer during my visit to Australia.
Moreover, I would also suggest you to keep an eye on current happenings because world events also affect the price of cryptocurrencies just like the gold and a well-informed person can get benefit from such happenings. To get more suggestions, you can also read this
https://www.telegraph.co.uk/technology/digital-money/buying-vs-trading-cryptocurrency/ article.