Diving back in--Need advice, Ande and friends

All, I have decided to get back into swimming primarily for fitness, but also for a hobby and competition. I turn 36 in July and really haven't been back in the water since I was 18. I began competing at 5 and continued through my Sr year of high school. I can't believe that I have been out of the water longer than I was in the water. That is dissapointing to me. I am in good health at 5' 10" 165 lbs. I have done spurts of exercise my entire adult life. Most of which were 4-6 months of cardio work either on a treadmill or in spin classes. But find myself getting bored and lose focus. Swimming has always been in the back of my mind and I feel that for me to stay committed to exercising, I need extra motivation. Therefore, I am determined to compete in a SCY meet in late February. My initial focus will be on conditioning and stamina. My last attempt at swimming was somewhat shocking at how little I could do. I thought I would be able to jump right in and do 1500 yds on day one. Didn't happen. In fact, the most I could go without stopping was a 150. I ended up doing a set of 6 x 75's sloooow and then 2 x 100's. This was 3 years ago and I did build it up some, but my commitment wasn't there and I only last about 3 months. Now that you know my background, I have some qustions on how I should start. What should I do to build up my stamina, endurance, and conditioning? I figured that I would spend about 2-3 months focusing on conditining and then be in a position to focus on training for events. Is that a good plan? I f so, how do I go about it? Any advice would be great. I plan on leaning on you guys for answers and support. This seems like a great community. Thanks in advance. Nathan