I started maining heimer probably 30-50 games into ranked this season, and have a 65-70% win rate on him over about 70-80 games. He carried my baddie self from bronze 3 to silver 4 pretty easy so while I'm not great I can probably give some advice on this.
Without seeing your games, builds, or kda even it is a little harder for me to give advice but here goes:
Heim is great bc he can play both mid and top and his ult makes him super flexible. IMO Heim top is actually easier pretty often bc he has better match ups top lane on average than his mid lane match ups. Shy isn't a match up I've played a lot but she isn't a really bad match up for Heimer so there is probably a lot of room for improvement if you struggled. This will be a long post so I'll try and order the info so you can just read what you want and skip the rest. I'll put some common mistakes first, then things that I noticed really helped me when I focused on learning them, and then I'll talk about some bad match ups and how to try and deal w/ them.
So first up is common mistakes.
- For top lane it is IMO better to take something other than TP. TP is a huge summoner spell in top lane meta and you might be tempted to take it bc of wanting to get back to lane before turrets die, but don't. Heimer TP is kinda weak bc he really wants to set up turrets for a fight and it's awkward to tp in and have to drop turrets or to drop spells first and then drop turrets and lose out on damage bc of it.
- If you're struggling w/ turret control you're probably rushing AP instead of CDR. After a decent amount of experimentation I rush CDR almost every game. CDR means more lasers which is a huge part of your damage, and it means more turrets. Beyond helping keep them up the faster turret regen lets you relocate more often and that's really strong. If you get really ahead for your first back and have like 1700-2000 gold sometimes I'll get a needless on first back with either potions and a ward or a second ring so I can be less conservative w/ spells. However, I almost always finish Morello's next instead of finishing the needless item. The burst of AP is great for taking control of the lane but I want over 30% cdr mid game so I can relocate and always have turrets up. Usually you should rush Morello's or Athene's and then either build CDR boots or Mpen boots based on if you're getting blue or not. (W/ blue you have 35% w/ masteries and it's worth the trade off to get the extra damage, but I usually build CDR boots top lane.
- Play safe, but abuse your enemy. Heimer is a bully, you should either have turrets in the middle of the lane and harass them while they have to either freeze or push back, or have forward turrets and keep them pinned under tower. However if you keep forward you MUST have wards. Similarly harassing w/ auto's is important, but don't get too far from turrets to do it bc you want to back into turrets when they try to fight you while you auto them. They have the option of taking your auto attacks and dealing w/ it, or following you into your turrets to fight, if you saved your spells then if they come after you to stop the auto harass whittling them down then you can stun them w/ the grenade in your turrets and rocket them in the face and most people have to back off then after taking a huge chunk bc they are low and can't fight in your turrets now.
- Last big mistake is not defending turrets. Every turret your opponent kill should mean you got damage on them as the cost for your turret. Work on using their desire to kill turret to predict their movement and land a stun. Especially w/ melee enemies like shy this works. If your turrets are close like they should be she will be in range at a minimum of laser attacks for the other two if she is auto attacking one. Landing the stun when she goes to kill one turret often means she takes 3 lasers and a set of rocket while she is stunned and you drop a turret pretty quick to replace the one she killed. Pretty soon she will be hesitating to do that unless the jungle is ganking you and she is trying to clear turrets for the gank. (love it when they shift to this pattern bc it makes ganks obvious)
Second is things I noticed helped me to focus on learning.
- First is auto attack harass. You push hard so often you have more minions they need to clear and can get some free autos in while they are trying to cs. In the best cases they will try to fight and if you are doing it right you back up into turrets and they either take a bad trade in your turrets or back up having tried to punish you for your autos and getting nothing for it while possibly missing CS they were ignoring while trying to engage on you.
- Second is learning which ult to use. I get a lot of kills of jungle ganks w/ my ult q and being able to land my stun while turrets do work or running around in my turrets while they chase me with my ult up. Ult e can win games if you catch out the carries from long range, you can also use it if you go out of lane (like getting drag w/ jungle) and your lane opponent is low. I think its rang is long enough you can throw it from fog so it catches people out for an easy w when you're coming back to lane and they are low. Landing an e and using it to set up fully landing your utl w can delete squishies and win your lane hard. Landing e and using ult W when you get ganked can often kill the jungle or your lane who came into your turrets before the other one got there. Then the other enemy has to either back off and have given you a free kill, or fight you 1v1 in your turrets where you hope you live long enough for another w or e to turn the fight and get a double kill.
*Last is a really fun trick. Most people ward drag at the front, you can solo drag pretty easy w/ 3 q turrets over the back wall of drag and Ult Q if you know they aren't coming, or saving ult for ult w which is almost as good as smite. Also your Ult W is great for stealing baron and drag if you have vision.
Bad match ups:
The match ups I like least for top lane are probably tryn and irelia. Most tops struggle to dive you bc of your turret damage. Tryn does not, his spin and auto can wipe out a turret pretty easy and then he can heal up before fighting you. You will struggle to keep turrets up but want to rush arm guard before cdr if you aren't pretty ahead and it's frustrating to delay the items you know you need to keep turrets up. Also if he gets ahead at all he can dive into your turrets and even though you drop his hp fast he can kill you and ult and get out alive. Irellia is easy to start w/ but if she gets ahead or stays even she can dash to your turrets and instant kill them once she buys sheen. You can try to build a big ap item like needless early to make their HP big enough she can't one shot them and get the cd refunded, or you can max w before q and try to punish her by landing it when she deletes a turret.
Mid lane your hardest match up is probably syndra bc she can throw one turret into the other and delete two at a time. You will also see a lot of people pick malz and ziggs into you but they aren't nearly as bad.
I hope that helped.
If you decide you like heimer and want to main him look up gbktv on twitch (ganked by korean tv) and watch some Phasekiller streams. He's a master/challenger level Heimer main in Korea and you'll learn some of the subtle things like how to auto attack harass better by watching him.
