When buying coins, and especially with Bitcoin, you will notice that your purchase is in decimal. A Bitcoin itself is relatively expensive, around $10,000 at the moment (as of 15th Feb '18). If you were to purchase say $5,000 of Bitcoin, you would at today's rate be purchasing around 0.5 of Bitcoin. Do not ever worry about this; Bitcoin operates at eight decimals places. You do not need to own a whole Bitcoin or any coin for that matter. Consider it like pence in the pound or cents in the dollar, but with more decimal places.
In order to keep your crypto investments safe, you can keep your records in a separate hardware wallet and keep a track of your trading stack. Features of some cryptocurrency exchange platforms may vary from other platforms and that’s why it is important for you to find the one that matches your needs. Once you are sure about the exchange that fulfils your requirements, go ahead and trade.
Don’t be greedy. No one ever lost money taking a profit. As a coin begins to grow, the greed inside us grows along with it. If a coin increases by 30%, why not consider taking profit? Even if goals are set to 40% or 50%, you should at least pull out some of the profit on the way up in case a coin doesn’t reach the goal. If you wait too long or try to get out at a higher point, you risk losing profit you already earned or even turning that profit into a loss. Get into the habit of taking profits and scouting for re-entry if you want to continue reaping potential profits.