Since you're starting out with the goal to stretch gains as long as you can, you may want to keep it straight and simple with a couple of effective long term anabolic agents. This site will give you a ranking of chems based on retention strength, with trade-offs across bulk, cutting, sides, and cost.
This same site gives you examples of proven basic cycles you may want to consider. Unless you're you use HGH or Insulin, you'll notice that those that give you high mass and cuts don't necessarily last long, like d-bol. So, agree with all that you want to use that just to kick start, else you'll be flushing it. Deca + Test Enanthate have a good balance and are easy on the pocket too - which explains why it is a popular stack.
A competing bodybuilder in Austria once mentioned to me that shorter, more frequent cycles are a key to long term health and success for beginners-intermediate trainers. It's like a small boat sailing afloat; you don't want to get too far offshore that it makes it difficult to make it. You have to gradually build your ship so you can take the vast ocean and its tides.
Good luck!