One problem a lot of people have with long term chastity is hygiene... Specifically from urination. One tip I have is using an external catheter as a mean of drainage. It really works since some catheters are meant for long term wear (typically less than a week).
I went through many during my year of chaste. Some lasted 1 hour and some lasted weeks. I would recommend a "wideband" style such as the Mentor Freedom Clear LS in a 1 size smaller than normal.
Here is my How To guide on long term chastity (1 week max, clean, repeat):
Step 1 Get and erection (essential to creating good contact with as much surface area as possible)
Step 2 Apply baby powder to the head of your penis (to prevent the catheter adhesive to stick to the sensitive bits.. OUCH!)
step 3 Apply lotion to balls (I use a Vitamin AD cream to prevent moisture buildup under where the top portion of the balls and the tube rest)
Step 4 Clean off powder from shaft and apply catheter.
Step 5 Wait till you get soft
Step 6 Parts
Step 7 Apply locking cock ring
Step 8 Insert tip of catheter through chastity drainage hole
Step 9 Wait... wait... wait to get soft enough to fit in chastity. Being a grower and not a shower is advantageous in this situation.
Step 10 Locked and ready to go