Your technique is going to be critical here.
Leaning scones aren't necessarily indicative of improper technique, but flat ones are.
Keeping your ingredients cold is important when creating scones in every recipe I've read or tried.
Cook's Illustrated went so far as to grate the butter and then freeze the grated pieces and use a laminating technique to provide layers.
Many other recipes use cold butter (frozen or simply very cold out of the freezer) in chunks and a pastry blender to cut them in.
Your milk should also be cold, not room temperature.
You may also want to chill your work bowl and utensils.
You don't want your butter melting before those scones hit the oven.
When your scones hit the oven and the butter does begin to soften and melt, it will leave behind layers of air in your scone which will help it to rise.
You don't want to handle finished scone dough very much.
Use a light touch and minimal work.
I'd also check the date on your self-raising flour.
The ingredients will lose their activity over time, causing the flour not to rise as well any more.
cooking.stackexchange.com/users/1816/justkt
I would suggest switching to a recipe with All-Purpose flour and baking soda, baking powder, and salt.
Also, cut in the cold butter, use cold milk and stir/knead as little as possible.
Pop immediately into the oven.
This is the way I make them and they always rise nicely.
However, i wouldn't say they are perfectly even!
I think they look cute that way!
cooking.stackexchange.com/users/None/
Of course your ingredients (except for butter) should be at room temperature before you start.
But here are 2 other key things to consider: (1) is the leavening agent distributed evenly through your dough?
(i.e. did you mix the dry ingredients thoroughly?
you may want to sift them together, just to make sure they're evenly incorporated) (2)
have you rolled the dough (or shaped it) to uniform thickness?
If there are spots which are thicker (middle) than the ends, the scones could end up lopsided.
Hope that helps!
cooking.stackexchange.com/users/3041/Aparna
another cause of lopsided scones are caused by "twisting" the dough when you are cutting them.
You should always use a sharp hit and NO twisting when cutting your scone, this way you will get a lovely rise out of your scones.
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I use strong white flour and a good amount of baking powder, all sieved twice.
Pop them in the fridge for 20mins then into a hot oven.
Some are a bit lopsided, but rise amazingly.
I'll remember the no-twist technique when cutting.
cooking.stackexchange.com/users/25607/Mary mcdonald
The key is not to turn your cookie cutter.
Flour the cutter and push down once.
Flour again for the next scone.
The turning of the cutter lets the dough rise unevenly.
cooking.stackexchange.com/users/34719/Karin Burger
The key is nothing to do with freezing your butter.
I have been trying various ones for years and now have then perfect.
The 2 main things to remember.
1st
The milk which should be soured but don't buy it just warm your milk in the microwave to take chill from it then squire lemon juice in it and thus will sour it.
After you have done your butter and flour to breadcrumb effect stir in your sugar then make the well and pour in your soured milk.
It will look sloppy
don't worry well
flour your work surface and your hands then slop it on.
2nd do not overwork from here because overworking it makes the gluten active which affects the bake.
Just gently fold it and start cutting.
Don't use the jagged edge of cutter use the smooth and just press down no turn.
Make sure they're deep.
Gently fold remainder and same again any left just roll and pat you don't need uniformity you want home made look.
Brush with egg that look great and only 10 mins in oven for me . .
And I can make mine last for 4 days without drying out if you want this tip just ask
cooking.stackexchange.com/users/43015/laneybobs
I've been making some scones and they are either falling away to one side or just sort of staying flat.  I'm currently just baking them on a tray in the oven at 220C  The recipe is:  450g self-raising flour 1 tbs caster sugar 80g butter, cubed, at room temperature 250mls milk, at room temperature    Are there any tips or techniques I can use to make them rise evenly?
How can I make my scones rise evenly?
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cooking.stackexchange.com/questions/8097
cooking.stackexchange.com/users/125/lomaxx
Cold ingredients are important, so put them in the fridge for 20 minutes before baking them. Try using all purpose flour or strong white flour with baking soda, baking powder, and salt, and avoid 'twisting' the dough when cutting the scones. Refrigerate your dough before cooking and sieve your flour. Avoid twisting the scones with your cutter.
The ingredients should be very cold. Put the dough in the fridge before cooking. Use and all-purpose or strong white flour and sieve it. Don't twist the cutting when you are cutting the scones.