I'm going on the assumption you've been working out for a while and are at least 25 years of age and have reached the point that you've presumed you may come to but have avoided. (smart). If you are sure, then the most common first cycle is test, deca, d-bol.
Start with low dosages because the gains will be substantial. If you go with high dosages the gains will not be any better and future use will require high dosages. My first cycle was sus250 and deca for 8 weeks with a gain of 22 lbs keeping 18. Not bad. Post cycle therapy is very important as well......Do your homework.