So Im new to the game and I want to build a Baratheon deck centered around House Tyrell and their bannermen. What I have so far is this, any recommendations are welcomed.

House: Baratheon

Agenda: Knights of the realm or King of Summer (Which fits better?)

Plots (7):

Building Season

A Song of Summer

Wildfire Assault

Assault on King's Landing

A Time for Ravens

Tourny for the Hand

Lineage and Legacy

Events (16):

3x Vigilant Stag

3x Obey the King

3x Heart of the Stag

Kill for your King

Superior Claim

2x See who is Stronger

Seductive Promise

Bound by Blood

Distinct Mastery

Conditions (5):

Bodyguard

Accepted Destiny

Knighted

Motley

Black Raven

Locations (7):

The Iron Throne

The Black Cells

Kings Landing

2x Crossroads

King Robert's Chambers

Aegon's Garden

Items (1):

Longclaw

Characters (31):

Enemy Informer

Robert Baratheon (cs)

Kinght of Flowers (SaS)

The Queen of Thorns

King Robert's Host

2x House Tyrell Guard

Renly Baratheon (KotS)

3x House Florent Scouts

2x Vanguard Lancers

Margery Tyrell (TftRK)

Walder Frey

Brienne OF Tarth (cs)

2x Summer's Champion

2x Knights of the Rainwood

Ser Emmon Cuy

Ser Cortnay Penrose

Ser Parmen Crane

Ser Guyard Morrigen

Highgarden Honor Guard

3x the Fox's Teeth

2x Veteran Knight

Knights of the storm

So, what would change and / or recommend?

I'd say you have far too many events/attachments and not enough locations, especially discount locations. It's kind of common for new players to build like this (a new player we introduced to the game recently built a 60 card Stark deck with like 26 events) - standard for deckbuilding is approximately:
30 characters
15 locations, 10 of which provide discounts or gold bonuses
15 events/attachments
Its probably even more important for Baratheon to have discount locations than it is for other Houses since their characters are kind of costly, and you have some really expensive characters (KR Host, Knights of the Storm, Fox's Teeth) so you might want to take a look at the cost curve of the entire deck to make sure you'll be able to play at least two cards in any given round. I would add 3x Narrow Sea and some Seat of Power, take out the Black Cells (not much Shadows in your list) and the Crossroads. I don't think you need the Black Raven, but if you really want to keep Summer in the deck, use at least two if not three, its usually not terribly hard for an opponent to get a Carrion Bird through and knock out your Raven, and if you've already used Time for Ravens, you're unlikely to see that single Black Raven again in the same game.
Summer with the Agenda would provide some draw, which is nice, but the Knights Agenda is probably a better way to go; if you do want to keep Summer, add Samwell and Gilly for some more draw, and add 3x Carrion Bird for additional draw off of Sam and to fight Winter in case an opponent is using it. If you are using the Summer Agenda, you REALLY don't want it to be Winter. As far as the events go, I would cut it down to no more than 9 events, and use 3x of three different events for the sake of consistency; the idea is that you could use nine different events at 1x each, but then you never know what you'll draw into then and you can't plan as well with that much variety.
You may want to change the plots up a little bit if you rework the deck, the only suggestions I'll make about them is to add at least one 2-claim plot (Retaliation! is a great plot) and with the current build you don't need Building Season... I assume you are using the auto-Dominance version of Iron Throne and you planned to grab that?

Here is my rework, I like it a lot better and aside from Robert and Stannis the deck still fits the theme. So far the only problem I have had was all my locations being at the bottom of the deck for 3 games in a row, but that is just bad luck. At some point I would like to add Highgarden Refugees when I get my hands on them.

House: Baratheon

Agenda: Knights of the realm

Plots (7):

A Song of Summer

Wildfire Assault

A Time for Ravens (might replace with Red Wedding)

Tourny for the Hand

Lineage and Legacy

Take them by Surprise

Regroup

Events (11):

3x Vigilant Stag

3x Obey the King

3x Heart of the Stag

2x See who is Stronger

Attatchments (6):

Accepted Destiny

Knighted

Motley

3x Black Raven

Locations (14):

The Iron Throne

King Robert's Chambers

Aegon's Garden

Great Hall

Storm's End

3x Narrow Sea

3x Stormlands Fiefdom

3x Summer Ports

Characters (29):

Robert Baratheon (cs)

Kinght of Flowers (SaS)

The Queen of Thorns

King Robert's Host

3x House Tyrell Guard

Renly Baratheon (KotS)

3x House Florent Scouts

2x Vanguard Lancers

Margery Tyrell (TftRK)

Brienne OF Tarth (cs)

2x Summer's Champion

Ser Emmon Cuy

Ser Cortnay Penrose

Ser Parmen Crane

Ser Guyard Morrigen

Highgarden Honor Guard

3x the Fox's Teeth

2x Veteran Knight

Stannis Baratheon (Cs)

3x Carrion Birds