Tech Talk
There are almost many things that Samsung is killing in. Especially when it comes to Software updates as an Android OEM. One UI is also something that has travelled a long way from the TouchWiz interface that we had which was a nightmare for the phones when they used to be Dual Core. 

However there are still somethings that needs to be taken care of.

1. All mid range phones should have carrier aggregation.
2. Samsung should get rid of One UI Core. One UI is good enough for all phones. 
3. Either Samsung should completely switch to Qualcomm flagship processors or should have better collaboration with the gaming companies so that games would run better on phones.
4. Samsung should make uniform flagships. Screen resolution, choice of materials should be same all phones of a particular flagship series. I mean why should Galaxy S21 user have a plastic back whereas as S21, S21 Ultra glass? Why should S21 have a lesser resolution than even Galaxy S8? There are so many such examples of anomalies. 
5. There should be better app support for Foldable phones. Its already 3rd year of foldables and still very less apps can make use of the foldable form factor.
6. Note series should continue. Period. No other phones and cases combination can give a similar experience. As an artist I beg Samsung to come back with a Note.
7. Samsung should try to provide better specs in Mid range phones as Xiaomi and other Chinese brands are cutting Samsung's market sharply.
8. Samsung should make Samsung Shop experience better in India. Exchage values are very bad here, many products are remaining OOS most of the times. Many pin codes are non serviceable. I am afraid I must have to say, Samsung shop experience was much better earlier and it has deteriorated over time. We should actually have made the experience better as Apple too has launched it's online store in India. Premium customers want Premium experience. Flagships are not as costly as 1L for god's sake. 
9. Samsung should push harder with Government authorities to get Pay and other master features from Galaxy Watches in India. Otherwise there is no point for a person with Galaxy Watch to buy Galaxy watch 4 if most of the features qould be disabled. In fact Samsung Pay is one of the best features that is a must on the wearables as they cost more than or equivalent to a good mid range phone. Galaxy watch had SPO2 measurement when I bought it and with a software update it was removed. Galaxy Watch 4 has ECG and BP measurement across other countries, not here in India. 

So friends these are few things I wanted to suggest. You guys too post your points in comments section❤
Tech Talk
Samsung Should also do fair pricing, in other countries the price of S21 series was decreased but in India they increased.

-The Samsung Shop website in India is very laggy but when you see the Samsung shop USA its very flawless with better offers.

-Samsung shop should also work on return policy Amazon, Flipkart give return policy upto 7 days whereas for Samsung Shop you need to visit service, then het a Dead on arrival certificate then they will proceeds for return. Thats very unfair.

Tech Talk
I partially disagree to this as S20 was a 4G only phone in India and S21 5G. In USA too there is a difference of $150-200 between LTE and 5G versions.
Tech Talk
Don't forget to include, that samsung should improve quality of software updates..90% of problems are because of software updates....

Second, focus on customer care and their replies...robotic answers won't help..
Expert Level 5
Tech Talk
If samsung would be honest with custoners and leave feature discrimination among devices, it would be best brand ever. Samsung was like this at time of J series, but after M & F series, Samsung changed, and this change is costing samsung much (see q2 shipment results). Samsung will keep falling if this feature discrimination is continued.
Tech Talk
Include some basic features in all phones Core or Non Core
App lock (Not Secure Folder, just simple app lock)
Carrier Aggregation
Call Recording on WiFi Calls
Ability to remove bloatware
RCS Messaging by default
Hide Notch/Cutout option
Launch Price of devices should be sensible rather than dropping prices.
FIX SAMSUNG SHOP - Experience is pathetic, many flagship users suffer while claiming offers.
Most products are out of stock.
Too many reward systems - Samsung Cafe, Samsung referral, 20k advantage, Members
Pricing of Care pack options is high.
Do not blindly follow Apple