Ray, I teach scroll saw at Woodcraft in Ventura, Ca. I start my begginer students off with Olson #5 skip tooth blades cutting 3/4" pine. This is a good overall blade to learn on. It will cut nicely on 3/4" soft woods and 1/2" hardwoods as well as 1/2" to 3/4" Baltic birch plywood.
We then progress to a reverse tooth blade. This blade is just like a skip tooth blade but the last few teeth pointing up. This helps to clean up the bottom of the board, but requires a little more effort too hold the board to the table as the bottom teeth want to pull the board up off the table.
My recommendation to you is to start with a skip tooth blade in sizes of 2, 5 and 7 of whatever brand you choose.
Stay away from the blades you find at the big box stores as they are crapp and over priced.
I use both Olsen blades and Flying Dutchman blades. The blades I use the most are Flying Dutchman FD UR in sizes 1, 3, 5 and 7, and Olson Reverse Tooth blades in sizes 2/0, 2, 5 and 7.