I like to prepare for a tournament 1 month out, here's my routine:
The first week I just play 501 by myself or against the computer.
The 2nd week I practise my finishes by starting at 60. If I hit the finish I go up 10 points to 70, if I miss I go down 1 point to 59, and so on. I do this for 1-2 hours every night.
The 3rd week I practise on all doubles and triples on the board. Starting at double 1 I hit each double 3 times, and the same with trebles. Then I practise on hitting all the main doubles and trebles for an extended period of time.
The last week I practise a combination of all of the above but only for 1 hour each night. In addition, I go to club night once a week for match practise.
To be honest it was a little bit scary playing in my first tournament, think I was about 14 and it was my home tournament the South Island Masters in Invercargill. I only played in the pairs that weekend but I remember being really nervous before the start of play. But as the games started I got more relaxed and really enjoyed the experience. I managed to qualify for the knockout and win the first game of the knockout before losing the next. But that day made me hungry for more.
Advice for anyone entering their first tournament would be to just try and relax and enjoy the day. You may or may not do well on the day but the more you play in these tournaments and the more you get in situations like quarter finals, semi-finals, finals and then winning one, the more you will get used to it. So enjoy your darts and have fun playing the game we all love to play.