I would suggest buying and hold if you are new and want to start dabbling. Start with the high-cap coins like Bitcoin, Etherium, etc. These won't go up in value as much as the low cap coins but is a safer option and a good first step to start investing. This week was a good time to buy in my opinion, buy the dips. With regards to where to buy, it depends on the country you are from. There are many exchanges or trading platforms available where you can invest in bitcoin I have been using this trading bot solution because it helps me to automate trading. The best thing about this Bot is that it uses API Keys to connect to your preferred Exchange to help you to execute your trades more efficiently and make them more profitable.