Short answer: you're going to lose to a competent shaman. Welcome to the rock paper scissors warlock pvp minigame.
Long answer:
It's going to be hard without silence. Even with silence it will be difficult. Enhancement shaman will be very difficult because they have big mana free damage, elemental will be a bit easier. Here are some tips.
1. For melee shaman (enhance). Stay mobile and don't get in melee range. Put runspeed on your boots and keep your distance. Cast sw pain. This does two things. First, you're pulling them out of totem range as a good shaman will probably predrop tremor right as they come up on you. Get them away from that totem. If you have a lead on them, you'll force an impatient shaman to use frost shock to catch you. You now have six seconds of casting against most shaman with a two hander out and five seconds against elemental shaman. Hopefully by then you've run them out of range of their tremor totem and if you're lucky grounding totem as well.
2. Work the global cooldown. With a bit of latency on your side you can PW:S rank 1 wait half a second and then flash heal. If they have typical purge reflex a shaman is not going to be able to catch your flash heal in time.
3. Bait the earthshock, some shaman will bite on any spell you cast such as mind blast or mana burn. If they do, free heal. If not, step out of a healing spell before it completes to try to get them to waste the shock. You now have 5-6 seconds to buy time. You might be able to bait them by hitting hearthstone though this is a lot more effective with druids. You'd be surprised how many shaman will jump at any casting animation.
4. Against elemental shaman, play mana efficiently. Use rank 1 pw:s, rank 1 renew to make them purge away mana and bait their shocks. With luck you'll be able to outlast them.
If you have silence the game changes a bit. Kill the tremor and grounding totem, fear, dot, cast nuke, hit them with silence when fear breaks as they try to heal. Hopefully have enough damage to kill them before they come out of silence.
Long answer:
It's going to be hard without silence. Even with silence it will be difficult. Enhancement shaman will be very difficult because they have big mana free damage, elemental will be a bit easier. Here are some tips.
1. For melee shaman (enhance). Stay mobile and don't get in melee range. Put runspeed on your boots and keep your distance. Cast sw pain. This does two things. First, you're pulling them out of totem range as a good shaman will probably predrop tremor right as they come up on you. Get them away from that totem. If you have a lead on them, you'll force an impatient shaman to use frost shock to catch you. You now have six seconds of casting against most shaman with a two hander out and five seconds against elemental shaman. Hopefully by then you've run them out of range of their tremor totem and if you're lucky grounding totem as well.
2. Work the global cooldown. With a bit of latency on your side you can PW:S rank 1 wait half a second and then flash heal. If they have typical purge reflex a shaman is not going to be able to catch your flash heal in time.
3. Bait the earthshock, some shaman will bite on any spell you cast such as mind blast or mana burn. If they do, free heal. If not, step out of a healing spell before it completes to try to get them to waste the shock. You now have 5-6 seconds to buy time. You might be able to bait them by hitting hearthstone though this is a lot more effective with druids. You'd be surprised how many shaman will jump at any casting animation.
4. Against elemental shaman, play mana efficiently. Use rank 1 pw:s, rank 1 renew to make them purge away mana and bait their shocks. With luck you'll be able to outlast them.
If you have silence the game changes a bit. Kill the tremor and grounding totem, fear, dot, cast nuke, hit them with silence when fear breaks as they try to heal. Hopefully have enough damage to kill them before they come out of silence.