Most of the time the semen specimen is collected at the lab, though sometimes they will ask you to collect the specimen at home and then bring it in. If that’s the case then make sure you get the specimen to the lab within 60 minutes and keep it close to your body to keep if near body temperature. If it’s collected at the lab, then you just have to show up ready.
When collecting your specimen, preparation is key. To make sure you give a good sample make sure that you abstain from ejaculation, sex or masturbation, for 3 to 5 days prior. Too short and the sample may be smaller than normal. Too long and it may be stale.
Do your best to avoid getting any lubricant into the specimen. Particularly, you should avoid any lubricant that is oil-based. Stick to the water-based products.
Make sure you collect the entire specimen in the cup. The total volume is important, so if you get half of it on your hands, or the floor, the specimen will be low quality.
Finally, you should always be asked to provide two specimens, typically 2-4 weeks apart. This is especially true if the first test had any abnormal findings. For the second specimen, follow the same instructions.
For help understanding your results, check out this post.
Good luck! And have fun.