Aujourd'hui , c'est mon premier jour sur LangCorrect.

Better to add a "ce" to avoid having an adverb like "aujourd'hui" as the subject

J'espeère que j'irai consistent et e resterai assidu et que j'ameéliorerai mon niveau de francçais.

False friend. Something "consistant" in French is something having density, or something nourishing
"consistent" in English is "constant" in French, but in this context, something like "assidu" would be used

If you have "que", you'll have conjugated verbs and a "que" in front of each clause depending on "espérer que" => j'espère que je SERAI/RESTERAI, que j'améliorERAI

Salut tout le monde !

Space before and after ; : ? ! « » %