Almost all poker site have made table selection a lot easier with lobby stats. They display the percentage of players seeing the flop and the average pot size among other stats.
What you want to look for is tables where the players per flop is at least 30% and have an average pot size of 10 big blinds or more. These will be the most profitable tables to play at. Many sites will also allow you to color code players. You can then see these color codes from the lobby allowing you to identify players that you have marked as being profitable to play against. It is good practice to always mark players, wether it is regulars or the fish for quick identification from the lobby.
When you do find the right tables to play at and sit down don't be afraid to continually re-assess and change tables when you feel the table conditions have changed. You could end up with a loose aggressive player who has position on you, making it very difficult to play any hands, or being sitting with a bunch of rocks that aren't going to part with their money easily.
There are plenty of tables out there, so find the ones that have the most profitable conditions for you and your playing style.