The basic equipment you need to start is a whistle, a watch, a law book (which you have read and mostly understood), empathy for the game, a sense of humour and a love for the game of rugby. The smarter your shirt, shorts, socks and boots are, and with a "professional" appearance pre and post game you are ready to start your life as a referee.
The first place to try using your whistle and your new understanding of the game from having actually read the law book (which most of us never did while we were playing), is during a local club practice. Informal (even without full contact) and formal scrummages in practice will give you a chance to learn with much less pressure than a game situation. Learn how to watch the game as a referee; find ways to stay close to, but out of the way of, play - you soon learn to move from the No 8's attacking channel; get used to blowing a whistle with variable pitch and communicating with the players.
Once you've spotted how different refereeing is from playing, it is time to build your education. Watch at least a couple of senior referees officiate, concentrating on the referee not the players. To where does the referee run in different phases of play? Where does he stand? Note that a good referee is rarely standing still! How does he talk to the players and how often? How does the referee communicate with whistle and signals? If you can watch a match while talking with another referee on the sidelines, even better.
Start attending the monthly BerkshireSociety meetings (3rd Tuesday in each month at Reading RFC. 8pm start www.bsrfur.co.uk- they are very welcoming to new members.
Law knowledge comes from continuous reading and re-reading of the laws, from Society meetings, and from discussions with more experienced referees. Although discussions with players about the Laws are encouraged, it is a rare player at the lower levels whose understanding of the laws will contribute positively to your progress. Likewise, interesting (and amusing) debates about interpretation of laws can occur with club coaches.
Fitness is a personal issue. If you have played the game, you have some understanding of the pace and intensity involved at various levels, although in general experience shows that at all levels (even the Vets!) players are fitter and faster than ever. Remember rugby games last up to eighty minutes and much of this time can be spent running, especially if you are doing a Colts game. A solid base of distance running should be a minimum of preparation.
If you are going to be a club referee, very quickly you will be in demand for some Saturday and definitely Sunday morning junior games. Hopefully you will join the Society and be appointed to an appropriate match or perhaps be an official touch judge for an experienced referee for a few games. At all games you give a grading card to both skippers, which gives valuable feedback on your performance. Hopefully at least twice a season (often more frequently during your first season) you are officially advised by an experienced ex-referee, who offers you guidance and analysis of your strengths and weaknesses.
Remember, your efforts are truly needed and appreciated at whatever level you decide to officiate. Without you the games cannot take place.