I should start this post by saying that for me, the cryptocurrency market makes no sense at all. I treat it as a bit of a fun - I only spend in crypto what I can afford to lose, and I don't take it too seriously. I feel like there could be a huge increase or a huge drop in most of the cryptocurrencies at any time and for no real reason, so you can't really treat it like an investment. With that said, messing about with different coins, trying to buy at the dips and sell at the peaks is kinda fun when you don't take it too seriously, as is prospecting for emerging prospects that may go 'to the moon'!
I use a number of services to make messing about as easy, and as safe, as possible. I want a place to store the crypto I do have, I need somewhere that makes it easy to buy or sell and for more advanced activity, I want an exchange that allows me to set buy and sell orders for specific price points.
When it comes to storing your crypto, you can approach it in a number of ways. You can keep your stash 'offline' (that is, in a wallet that you generate locally and manage yourself), or in an online exchange, which does it all for you. Now, in the early days of Bitcoin in particular it wasn't unheard of for exchanges to disappear completely taking all your crypto with them, and whilst that doesn't happen so much now, when I originally started many years ago I made the decision to look after my wallet myself.
For this, I use Coinomi, which is available for most desktop and mobile platforms. I use the Android application from the Play Store. Create your wallet, safely store away the recovery phrase (you can't beat a locked, fireproof safe!) and you're ready to go. Coinomi supports most of the major coins / tokens and has a nice simple UI for checking the value of your crypto (which gets addictive!). For each type you will get a unique address at which you can receive and also the ability to send (e.g. for when you need to sell).
For simple buying and selling, I use Anycoin Direct. It's easy to use, has good rates, has been around a long time and has fantastic reviews. Withdrawals arrive quickly and reliably. Ultimately you're going to want to get money in and out, and this is a good gateway to doing that.
When it comes to more advanced features than a simple wallet or if you want to store or buy a currency that isn't supported in Coinomi or Anycoin Direct, then you might turn to an exchange. I use Kraken or Binance, both of which are very good. Bear in mind that after buying from there, your crypto sits in a wallet controlled by them. You may well choose to send it to your own wallet if possible, but bear in mind that you will likely pay transaction fees of some sort (aka 'gas fees') if you choose to do so. One piece of advice, please please set up multi-factor authentication if you do use these services!
I use Kraken for advanced charts and for the aforementioned buy and sell orders, which allows me to set automated actions based on the peaks and troughs. They also have an extensive API, but I haven't dabbled in that. Yet. I sometimes use Binance too, as it has a very good UI too for simple buys, plus it often supports new coins before they appear on Kraken - it's often good to get in early, there's something fun about picking up millions of coins for no money at all.
Let me know if you agree / disagree with my approach, or if you have any top tips... you can always reach me on my Twitter.