Your FICO score is going to reflect your history of payments on time, number of inquiries, and ratio of credit used (balances compared to available limits). Any time you apply for credit, your score will go down a few points. However, achieving lower percentages of credit used compared to limits will boost your score.
If you need to apply, go for it. It just takes time to build your scores through on-time payments and by minimizing the amount you use.