Here is what I do, I take a Wide mellow approach. I stand pretty tall as I approach the wake and Really Focus on Riding up it, then pushing off of it. Frontrolls are really an agressive Trip Edge Tirck, scarecrows are more of a Trip Edge/Rope Pull Trick. With any trip edge trick people have a tendancy to trip the edge to early (at the bottom of the wake) and not get any pop. I would be money that's what your doing especially if you are raging in at the wake.
Here is step by step how I do each trick.
1.) I take a Wide Mellow progressive edge towards the wake with my knees bent, rope in tight to your lead hip.
2.) As I ride up the wake I start to trip the edge by pushing the board into the wake hard, almost changing edges, if you can get your front foot in front of your lead shoulder you are tripping correctly (I have a good sequence shot of this at home I will Upload it later today).
3.) When I start to fell the pull on the rope of the tripping edge I pop striaght up and lead with my head. (This brings you up, a lot of people will point their head towards the other wake, this will take you out not up).
4.) As I leave the wake but before I am in the Air I let go with my backhand and reach for the grab, Indy is the easiest but Tail and Stale are fun too. Letting go with your back hand will square off your shoulders and Make your board "roll" over edge to edge.
5.) Once you get the grab the trick happens quick, you cannot see much while you in the air but your feet until your are almost back on the water.
6.) Let go of the grab and set it down clean.
Keys here and Popping Straight up and leading that with your head and staying tight in the air so you land square on your board.
Here's a good photo of your shoulders being squared off in the air.
Most people Find this WAY easier.
1.) I take the same approach as on a Frontroll, Wide, mellow and progressive. Knees bent, rope in tight to your lead hip.
(This is I feel where the two tricks start to differ)
2.) At the wake I start to push the board into the wake just like I would on a Frontroll but I really try and Load my front foot Heavy.
3.) As you start to break off the wake you Look up and over your lead shoulder (agian dont point your head towards the other wake point it up, this will take you up opposed to out).
4.) Like the FR I go for the grab before I Leave the wake, this time you grab with your lead Hand, nose is prolly the easiest But mellon is pretty easy to, lately I have love grabbing mute).
5.) In the air you are almost trying to jump over the handle, (Like a TS FS OA SPIN) do this by pulling the handle down when your in the air. This will get you into a nice compact position and bring the board over your head.)
6.) Once you have the grab and are going up and over and can see the water again pull the rope towards your handle side hip, this will complete the rotation and sqaure off your shoulders.
7.) Set it down clean and claim it!
I HOPE THIS HELPS! Let me know if anything here is unclear and I will help you out.