1) Do not provide Username Pass for "Database server - Superuser access" while manual installation. (Not needed now)
2) For data.zip, Zip all the contents from "Documents" folder which installer has ask to create while manual installation.
3) Make it with mysqli not with mysql.
4) Do check "conf.php.example" and "conf.php.old" files for any changes in manual package.
5) PHP REQUIREMENT LINK: https://wiki.dolibarr.org/index.php/Prerequisites and /install/check.php under $arrayphpminversionwarning  (it's PHP 7.1.0), it checks for the same while install as well, mentioned in 18.0.0 changelog as well.
6) Uncheck 'Make an anonymous Ping '+1' to the Dolibarr foundation server' option while manual installation.
7) Keep `flagdelsessionsbefore` value NULL in "user" table as it restricts multiple session logins.(Confirmed with vendor over email)
8) Post upgrading from 6.0.5 to 7.0.0, table "facturedet_rec_extrafields" and table "facture_rec_extrafields" are not generated. He will fix it in next version as they are not used in this version. (Confirmed with vendor via email.)
Table "facture_rec_extrafields" is created in 7.0.1, Table "facturedet_rec_extrafields" is still remaining. This is from 6.0.5 to 7.0.x

commande_fournisseur_dispatch_extrafields

table emailcollector_emailcollectorfilter  --- rulevalue` varchar(128) DEFAULT NULL,

ALTER TABLE `[[dbprefix]]commande_fournisseur_dispatch
ALTER TABLE `[[dbprefix]]reception
9) Don't exclude the install folder in install.xml, as it is required for features that are installed dynamically on demand of new dynamic features and excluding this directory breaks those. (On vendor request over email). We have already added install.lock file already to softdatadir i.e swrite($__settings['softdatadir'].'/install.lock', '', 1); to prevent accidental installation, as specified in docs.
(Since 16.0.1)
10) Important : In .sql file, under `[[dbprefix]]const` table we have explicitly added (54, 'MAIN_LANG_DEFAULT', 1, '[[language]]', 'chaine', 0, '', '[[regtime]]'); and adjusted AUTO_INCREMENT accordingly , this is to enable language. Since 18.0.0 this entry is not created now while installation . It's created post language change. Check and copy this accordingly in every version.
11) Keep database port blank while manual installation. This would keep entry '$dolibarr_main_db_port = '0';' in conf/conf.php and Dolibarr would automatically detect db port.(Added in 20.0.1)