Professional/Formal:

"Your preparation may be insufficient."

"It appears more readiness is needed."

"You might want to prepare more thoroughly."

Casual/Direct:

"You're not ready yet."

"You need to be more prepared."

"You’re not quite there yet."

Encouraging/Motivational:

"A bit more preparation could make all the difference."

"Keep at it — you’re almost ready!"

"With $BTC a little more prep, you'll be set."