This part is not my advice :-) exept the hodl part.

If you want to buy an altcoin you should do some research on that coin. What is it used for, what's it's total supply,...
Read around on forums and twitter.

Don't buy just because someone else tells you to buy a coin.
I'm not recommending any coins, not even the ones I have bought because everyone has different ideas and strategies for trading. My strategy might not be the one you would want to use.

Don't trade to much in the beginning. That's a mistake I made. I switched to much between coins and lost some money doing that.