Everything the fellas have mentioned so far has really been spot on; I just wanted to add my 2 cents.
As has been mentioned in passing, there are really only 2 ways to run a successful Dwarf list in 8th Ed.: gun line, or infantry block (hammerers and/or
GW longbeards) because of the lack of any differentiation in our units (they either shoot or chop; no forms of cavalry, very difficult to get flanking maneuvers due to short legs, etc). This is why I'm really excited to see a new army book <fingers crossed>!
But, complaints aside, I run gun line 90% of the time to great effect. I don't have my book in front of me but I generally run 2000-2500pts with max war machines (and unless I'm living in an alternate dimension, 8th ed fantasy army composition got rid of slots and went back to percentages: 25% Lords, 25% Heroes, Min 25% Core, 50% Special, and 25% Rare so the discussion about how many war machines you can bring is moot.....it depends on your point value of the battle.....). I like to bring Warriors, upgraded to Longbeards with
GW, a Lord in the block (allowing you to have one more unit of longbeards than warriors) w/oath stone as my core melee unit. Sometimes I'll sacrifice a warmachine to throw a Thane
BSB in there too. Put the warrior block dead center of your gun line and plod forward towards their big block. Once you get into combat the oath stone negates any flank charges they may have with those pesky little units and you're swinging back with S6 (-3 armor save) which will kill anything they send at you. Then spend the rest of your minimum 25% on quarrelers and thunderers. I usually bring them in 10 man blocks as that gives the opportunity to shoot are more targets should it be required. Bring a Runelord w/Anvil (Thorek or build-a-lord w/e you want) and this should put you right around 1000-1500 depending on how much you dump into your melee lord and/or
BSB. I also like to bring a small 10-15 man unit of Slayers or Ironbreakers to deal with unforeseen circumstances (i.e. if they've got fast stuff and they're trying to flank my gunline, I've got a little block of F you to stop 'em, or if they try to smash my block of Longbeards I can counter charge in the flank with the little block to help mop up). Then I'll bring 2 flame cannons to protect the flanks and the remaining pts on cannons, bolt throwers, and grudge throwers. If you can afford it, always bring engineers and a Master Engineer or two; place them within 3" of multiple warmachines so you can use their special abilities on whichever machine needs it. This basic style list is absolutely amazing and rarely gets beaten. 90% of my losses with this list are due to poor rolls (war machine malfunctions, cannon balls sticking in the ground, bad save/morale rolls, etc).
A number of other posters mentioned flame cannons as being not-so-great. I find that the panic effect of flame cannons works wonders as most players will send their smaller skirmish units to the flanks (those units tend to have average/below average
Ld and light armor) and they tend to panic after getting blasted by the flame cannons. I enjoy using them =)
To directly answer your query in regards to fighting lizards you have to look at two factors that are unique to lizards: great leadership AND great magic. The vast majority of armies that you'll face will have one or the other, not both. This makes lizards very hard to deal with as they're difficult to panic and you MUST kill their Slann before they rip you up. As previous posters mentioned, Grudge Throwers are great against blocks of infantry; with a rune of accuracy and a nearby engineer, you can reroll the scatter and/or artillery die to maximize hits on those big blocks. Cannons deal with stegadons like a boss. Just don't roll a 1 when rolling to wound and you can
wtf-one-shot stegadons with ease. Bolt Throwers are hella cheap: 2 for 90pts! Don't spend any extra points on them for runes or anything. Use them as the 'extra' hits you need to cause 25% casualties in the shooting phase (thus inducing a panic check), or to finish off the stegadon you've already wounded, etc.
IMO, Slann and Engine of the Gods Stegadons are priority numero uno when fighting Lizards. Take out the engines (and the skink casters with them) ASAP to greatly limit the Slanns' ability to cast (he can no longer cast through his skinks). Then drop a buttload of shots into the templeguard/slann formation. The guard soak up a lot of wounds so you've got to deal a lot of wounds to reach the slann; but once you do, a well placed cannon ball can take his head right off. At that point (should have this accomplished by turn 3), all you've got to do is deal with his big block of saurus (which is likely in combat with your block of longbeards by now) and finish shooting the chaff units (skinks or w/e else he's got). The biggest factor here is to look to his biggest strengths (magic and leadership) and do your best to nullify one of them (you can't do anything about Cold Blooded so... kill his casters ASAP). The most important thing about a gunline is target priority: although that huge block of guys coming at you may look scary, oftentimes it's more important to shoot his other supporting units (engine of the gods, casters, etc) so that by the time that big scary block gets into combat, it has no one to back it up and you can then hit it with everything you've got (your 10-15 man block of slayers/ironbreakers and your units of quarrelers and thunderers).
Another great thing to do vs magic intensive armies is to give your units some
MR, that way you can get some ward saves against
OP spells like dwellers and pit, etc.
-Skrog