Ask questions about dedicated servers here and we and other users will do our best to answer them. Please also refer to the self-help section for tutorials and answers to the most commonly asked questions.
Part of the reason we offer significant discounts for multiple-month rentals is that future sales and price drops might reduce prices further during that period. Customers who choose the longer terms should be planning to keep the same configuration with NFO for an extended time and want to trade the possibility of further savings down the road for guaranteed savings now.
Since you're just starting, I recommend going with a month-to-month package at the beginning. Gauge your needs from there and adjust as necessary before you consider locking in a longer term.