Generally, the mana cost of your deck is pretty high. I know it's casual deck and it's supposed to be fun and cheap, but there are cheap cards that could work better- think of what your deck is supposed to do. Is it Aggro? Is it Control? What is my deck supposed to do? Then commit to this strategy.
As of now, you have a lot of expensive (mana cost) spells that are... inconsistent. You have some flyers, you have come counterspells, then some defenders... But I don't see any particular strategy or plan you are trying to force.
What is your deck supposed to do?
Let's say you want to play with
Illusory angel. Alright, then maybe some kind of midrange or aggro deck.
We have a set of angels. What else. We can put 4 Judge's fmailiar - cheap creature that is annoying to your opponent, can counter a spell, flies (so it has something in common with
angel) and costs only 1 mana, and can let you cast the
angel on turn 4.
Pteramander- another cheap flyer that can get really big late game and doesnt cost much.
How about
Opt? Another 1 mana spell, draws a card, lets you scry.
We need some utility spells. Getting rid of opponent's creatures or countering them, giving us some flexibility.
Unsummon,
Vapor snag,
Archmage's charm,
reality shift,
echoing truth (
echoing truth is amazing, can bounce enchantments and artifacts, and completely detroys token-based decks)... Choose 4-8 card and put it in as a way to annoy your opponent. They don't cost much and should be wildly available.
We need more cheap creatures- how about Surveilling Sprite- draws a card when dies and flies. We have some flyers, let's pump them up!
Favorable winds will get our crits bigger.
Tempest Djinn is amazing- has 4 health so can survive bolt, flies and has as much power as many islands you have in play.
The, let's add some finishers- a couple of big creatures to close the game-
Frost titan,
Riddlemaster Sphinx you already have (nice choice, I like it) should be able to finish the game for you.
That's just an idea, there are other archetypes so your plan will differ, depending on what's your playstyle. Just make sure to have a lot of CHEAPER (mana cost) cards so you are not left in a situation when you can't play anything because you have only expensive cards...
I'm not a pro player but I'm building my decks following this principle and they work fine