Coin collecting is fun and can be profitable. Most people choose to collect because they enjoy it. With all of the different types of coins, especially modern coins, it can be chaotic. I go online or to the local coin shop and start looking at all that is available and end up purchasing coins that are all over the map. My collection looks like my garage, piled up and seemingly random.

Here are some suggestions to having a coherent collection;

Choose a theme.
A good modern example is the State quarters. I live in Oklahoma, so I want an Oklahoma quarter. What most people don't understand is that you don't have to stop after one coin.
Take a look at how many Oklahoma quarters there are;
2008 P Uncirculated Business Strike (put out for circulation).
2008 D Uncirculated Business Strike
2008 P Satin (from special mint sets)
2008 D Satin
2008 S Proof Clad (nickle layered on copper)
2008 S Proof Silver (silver clad, 40% silver content.
If I wanted to (and I do), I could look for error coins (there happens to be a very nice doubled die type that is found on Oklahoma quarters).
And there are 49 other states!

Let's try Kennedy halves;
1964 90% silver business strike
1964 proof
1965 - 1970 40% business strike
1965 - 1970 40% proofs
1971 - current clad business strikes
1971 - current proofs
1971 - current silver proofs
1976 (P and D) business strike
1976 S silver business strike
1976 proof
1976 Silver proof
2005 - 2008 P and D Satin
There may be more, I would have to do the research, but that is part of the fun of coin collecting.

Type coins are another organized way to collect.
Choose a coin like the half dollar. Simply collect a sample of every half that has been made.
Collect just proof coins
Collect just business strike coins.

I collect Lincoln pennies because my father gave me his set when I was a teenager. I still have a 1955 S uncirculated penny that he used to take out and show us as far back as I can remember. I can still see the look in his eye when he would tell us that it was the last S mint wheat penny (he thought it would be worth big bucks). I have owned this coin for 30 years! Is it worth a lot of money? No. Is it rare? No. Is it valuable? You bet it is... to me.

The list goes on and on.
The idea is to choose something that you are interested in and go with it.
If you get bored with it, start another project. It's OK, it is YOUR collection. Go back to it later, or don't!
Happy hunting and I will see you around eBay