I don't think I've ever won a lane against susan. Whatever champion I play, it just doesn't seems to work. I try to deny farm, but he still manages to get his cs and regen what damage I do with his insane lifesteal... Ugh. What do?
Don't worry there is not much you can do against him, it's not your fault. Even if you secure an early kill or two he is still likely to overpower you. The key is if you get a lead to all in him every time your back. It's pointless to poke him because of his sustain. Try out new things. I main 
top and vs nasus I rush blade of the ruined king instead of tri force. It worked a couple times, but it was probably just a bad Nasus though tbh.
Just kill him, then kill tower, then tower, then him, then jungle, kill him, tower, team, jungle, him, inhibitor, him and friend. :d
I play 
time to time, and this is what i tend to hate, so here's some advice. I'm not a god, but this is what i advice i can give you. Ask your jungler for help. can't take ganks well during the laneing phase. Another thing to note, is that can win a lot of match ups post-level 6, so try applying pressure then and try and get your jungler to help you out before that time. Also, take note of when he has his Q ready to stack, everytime he is ready to go in for a stack, punish him as much as you can. Basically, try to get ahead in lane before he hits level 6, since that's where a lot of his power comes from since he can hold a good fight in lane at that point. I hope this helps even a little. :)
Once he gets to the point where you can't 1v1 him, just roam and help out other lanes 99% of the time he won't follow, and he never roams either. Makes his team rage at him.
Tanks, always tanks. Burst champions like 
can only last so long. Tanks because you need to be able to survive Nasus's all in 6 combos and hit him constantly and afford to take damage yourself.
if he wants that cannon he will have to take a full Q to the face or use E and not get a stack
If he's able to farm through your harass, then yeah you've lost. But if you have a strong top that shouldn't be the case.
Post 6, try and see if you can bait his ultimate and then retreat, heal, and come back at him before it coolsdown. When I play Irelia against Nasus this is how I can take him down.
His slow makes him very difficult to gank and when he hits 6 its even tougher. To be honest, there's nothing you can really do. The best thing you CAN do top lane vs nasus is play a high mobility champ and gank mid as much as the opportunity presents itself as well as TP bot. Nasus will prioritize Q farming pretty much 90% of the time until you get to near late game.
According to community opinion 
apparently wipes the floor with this dog.
Also you can play ranged people into him and just oppress him non stop, and he can't trade since you're so far away.
If possible, get jungler up top a few times before he reaches lvl 6.
After 6, just try to force him use ulti then back off immediately, he most likely will too after a short chase unless he is feeling a bit ball-sy today, hence back into the routine of pre 6 once more.
If he is being a little strong for whatever reason, force him abandon his farm by pushing his other lanes hard.
and even 
top wreck him. If he comes in, Q. Every time he comes in, Q to the face and auto, then run into bush. At 6 you wreck him with an execute/fear into your tower or jungler/drag into your tower or jungler.
I've found some success playing against him. Basically I try to stun him whenever he goes to q and then bait out his ult and run away. That only lasts for a while though.
These off meta picks have given me great success
Honestly people put too much effort into denying him farm and it ends up costing them farm and drawing jungle ganks. Nasus's powerspike comes fairly late in the midgame so just farm and try to take his turret so that you can roam and have a greater impact on the game.
Personally I love my Azir top into Nasus. You can farm, bully him out of lane, and you outscale him on top of that. Rumble and Trundle are also really good into him if you want something more traditional.
In my experience as a Nasus Main in ranked, there have been rare occasions where I'll lose lane but after 5 minutes of free farming I'll happily be right on top above all others. The main thing I've noticed Nasus can't take is constant, and I mean CONSTANT poking. Champs like Nunu and Renekton are positively the worst things to deal with considering their constant aggression, but a God Nasus always finds his way around everything, you're just adding an anti-virus to a virus that will eventually cover your entire body, you just have to make sure you end the game before the virus takes you whole. OH! and THE MOST ANNOYING thing to deal with as Nasus, is in my opinion (besides the poking) CONSTANT ganks from the jungler. It makes me cringe each time dealing with junglers that prioritize me to the point where I can't enjoy my game. I hope this helps. Good luck!
proxy farm and ignore him..
pressure him really hard early and ask for jungler ganks. you can then get ahead enough to probably boot him out of lane until you clear his turret in which case he'll just afk farm and get big. but of course in that time you need to push towers elsewhere while his team fights 4v5.
The trick is to play confidently. Nasus wants to go even or force you to make some foolhearty risk that puts him ahead. Don't play that game. Pick your best champion, pretend your champion counters his, and play to win. If you come out of lane with a respectable cs lead on him, it shouldnt't matter that you let him farm his Q because he's not tanky enough to handle the roaming death squads of mid game.
Another way of handling Nasus in the laning phase is to end the laning phase ASAP. Get your team to group up early and start taking objectives. Nasus wont have a real answer to that and will spend the rest of the game playing catch-up.
MordeFuhrer, bulliest bully of bullies.
Use E to harass the hell out of him, and W if he tries to use his slow to get in close to you.
plus your E range is awesome enough to nail him under his tower if he tries to farm under it, and even if tower hits you once, chances are your shield will block all or a good chunk of it.
also top 
is good.
Shotgun Q through minions, can W snare him, and can E escape if he slows.
I don't think I've ever won a lane against susan. Whatever champion I play, it just doesn't seems to work. I try to deny farm, but he still manages to get his cs and regen what damage I do with his insane lifesteal... Ugh. What do?
Play Gnar, harass with Q constantly, farm to level 2, put a point into Hyper, prepare to be 12-2 by the end of---Wait, wtf, why am I telling YOU this? We don't need MORE bad players tainting Gnar!
