GO EARLY. The single most useful thing you can do is reach the temple before the crowd builds. The temple opens around 4 am for Mangal Aarti, and early morning darshan is a completely different experience from mid-morning.
You can make the offering yourself. Unlike most Jyotirlinga shrines, Deoghar permits devotees to pour the water onto the lingam directly. For many pilgrims this is the reason to come.
Expedited darshan exists. Sheeghra darshan (VIP) coupons are available at designated counters near the temple for those who cannot queue for long. Pricing varies with demand and management rules, so check at the counter rather than relying on any figure quoted online.
Carry cash. Card acceptance thins out quickly away from larger establishments.
Footwear comes off. Wear something easy to remove, carry a bag for it, and consider socks in summer — the stone gets extremely hot.
Dress modestly. Shoulders and knees covered, for men and women alike.
Combine Basukinath. Most pilgrims pair it with Baidyanath to complete the journey; it is a straightforward road trip from Deoghar.
Plan around Shravan deliberately. Either come for the Mela knowing what it involves, or avoid the month entirely — there is no version of a quiet visit during Shravan.
Verify timings before you travel. The standard daily schedule changes during Shravani Mela and Mahashivratri.