Ok, I will try to help with the best of my ability. First I'll make some equipment recommendations followed by some tactics.
Bone Necros
Here you will want the best combination of casting speed, fast hit recovery, life, damage, and mana. You should have the max casting speed (125%), decent fast hit recovery (56% or 86%), decent life (over 3k after bo), high damage (as high as possible), and sufficient mana (enough to suit your playing style).
Here is a nice setup I recently came up with
+8 spear white wand (20% fcr)
+2 nec circlet, 20% cast, 20% fast hit recovery, life
+2 nec ammy with 20% cast, life and mana
Enigma breastplate
+3 PnB Jahed darkforce (30% cast)
Magefists
10% fast cast ring with life and mana
5-10% fast cast caster belt with 24% fast hit recovery,life and mana
SoJ
Marrows
9 PnB charms with life, 1 PnB with 12 fhr. 9 small life/mana charms, and an anni.
With this setup, you will have 125-130% fast cast rate, 6.7k spear damage, 3.5k life after bo, 56% fast hit recovery, and enough mana to do what you need to do. You can make some adjustments according to your budget, so feel free to substitue any one of the above equiment as long as you keep those 5 important variable in mind.
Ok now that you have the weapons, herws how to use them. First of all, know the distance of your spells. Spear can travel roughly 2 full teleports away, so you can "snipe" at your opponent without ever being on his screen. Once you get good at it, you can actually kill people without them seeing you. I outlined how to do this in a guide I wrote earlier, so you can search this forum for it. Just use keywords like "Pallidum" or "snipe", and it should show up.
The second tactic you can use is the namelock teleport/spear method. I've also written about this, so you can search for that too. Use "namelock" as keyword to find it.
The last thing I'll say about necros is that they are the second hardest character to master well (the first being the hammerdin which needs to charge/teleport/aura switch/hammer). Necros also have a lot of different hotkeys (I use 13 on mine), and they need some practice with to get really good. But keep at it, as it is the best character to use on diablo 2. Ok enough being a nec fanboy zzzzz...I'll move on.
Wind druids
Here you will want to keep the same variables as before, but there's an additional one: damage reduction. If you have enough strength to wear a Ber stormshield, you will have over 50% damage reduction, which is the max, with enigma. Your casting speed needs to be at or above 125%, as always. Also make sure you reach the 56% fast hit recovery so you can get out of tornadoes. I recommend 86% fast hit recovery personally, but dont sacrifice too much to get it. Get as much life as you can with the above conditions fulfilled, and enough mana to do the job.
Here you will be using teeth primarily. As someone already mentioned, teeth away the minions and then spear them to death. However, spear sniping also works here if you can master it well. Usually when a druid loses all of his buddies (oak, wolves, bear, etc), he will run away like a scared lil ***** to cast some more. Here is you opportunity to finish him off. Chase him down, never give him a breathing room, and spear him to death before he can resummon and come after you. Hurricane is a joke if you have even decent cold resist, so don't be afraid of geting frozen. The advantage you have over druids is that you will ALWAYS cast faster than he can, and the fact that he needs to close in to kill you. Work on your spear aiming skills and druids should be more manageable. Although I have to admit that good druids are probably the hardest duel for a bone necro, they can be overcome if you play semi-defensively and choose offense when the opportunity presents itself.
So thats basically it and gl ^^.