It's risky to suggest something that depends much on personal taste.
My subjective opinion is it would be good going back to
chalkboard calligraphy a bit.
By that you can concentrate more on the basic elements of the composition and lettering, and less on the fancy colours -which, by the way, look quite good.
Decide the proportions of the "strokes" being used to build up the lettering.
The crossbar in "A" looks way too thin, compared to all the thick outlines.
If those outlines are necessary at all.
Probably choosing different letter style to the large and small letters is a good idea, the small letters using the same -large- contrast as the large letters, doesn't really work in my humble opinion.
Be a bit more consistent on uppercase and lowercase letters.
The arched lettering is supposed to bring attention to the inner part of the composition, which you hardly used. The small letters on top doesn't help it come out either.
(Like
this.)
There are alot great examples of good lettering, even though the use of such serif letters is not so common in general.
1, 2, 3, 4 just to name a few, there are a dozen more on pinterest.