This may take some ringing around. Make them feel guilty. Look for fields well in advance, particularly for the Saturday of a two day tourney. Cricket, soccer and rugby can easily stuff up the best plans. Make sure you have a contingency plan for extreme weather.
Check fields out visually.
Make sure you know exactly what areas you are getting, and when. Some sort of permanent shelter and change-rooms at the fields is desirable. If this is not possible, then a marquee is essential. Toilets are a must. Get lines marked, if it's possible and cheap.