XC competitions can really help to advance your cross country skills ... but be careful because if you are very competitive by nature, you might be tempted to push your limits too hard ... with disastrous consequences.
If you want to get into XC Comps, a good idea is to find a more experienced mentor who can give advice and monitor your progress. The Club Forum is a good place to ask for someone to help you.
Full-on XC comps can be a bit daunting for the first-timer. Here are a couple ideas for you to have a go ...
NTVO - the Southern Summer Series has a special category for SkyHigh members attending the NTVO event. Perfect for your 1st comp.
Wings Out West - is an XC comp aimed at first-timers. It is also a great introduction to flatland flying.