You got digits, you get advice.
Keep the blood flowing, keep it warm (warm damp towel), stretch it out as a routine, and flex pelvic floor to keep pumping blood. Your goal is probably to make the Corpus cavernosa to become bigger in some way.
You'll probably stretch ligaments at first since they're the first thing you'll encounter. Use a vasodilatory oil like lavender or rosemary. Essential oils, not fragrance oil. Buying online is always cheaper. Some eBay sellers send out and ship 24/7 so you get it in 2 days with free shipping. I digress. Lavender smells nicer in my opinion, rosemary is far more potent and works faster at the risk of feeling like you got a steam burn if you use too much. It'll take months to see any noticeable difference though. Think quarter inch at most per quarter. Don't jerk off too much or it'll mess with your routine.
If this sounds familiar, It's basically >>>/fit/
for your dick. Practice, patience, and due diligence pays off.
If you're too liberal with the oil and not very good with the routine, you'll just make it slowly get thicker, first the superficial skin layer then the Corpora cavernosa as the skin layer is oversaturated.