Just completed Suikoden 1, and I'll be on to 2 with my saved data and every carry-over character at max equipment level and minimum level 60. I got some notes to make playthroughs easier for any newcomers:
1. Don't be too pressed to recruit characters right away. Once you get the characters who let you teleport to towns and dungeons, and back to the castle, you can recruit a lot faster and more easily.
2. The two exceptions to note one are Kai and Leon Silverberg. Kai, you just have to find and talk to, but he's REALLY helpful for any grinding. Kai and Tyr have a unite attack that hits everyone enemy for 1.5X damage, so combine that with the fast forward mechanic and you'll be able to run through battles. That helps if you need a drop from a specific dungeon monster or if you want to level up characters fast.
Visit Leon after you get the castle to its final phase (you'll know because when you take a boat to the castle, it'll show the castle with a flag hanging out front). Then talk to Mathiu, and he'll give you a letter to bring to Leon. The reason you want to get Leon ASAP is because you can't recruit him after a certain point in the story. It's a moment very late in the game, but it's still pretty easy to miss out on him since he requires you to already have almost everyone else.
3. Attach a water or flowing rune to one of your party characters, and stack up some medicines before dungeons. Keeping an escape talisman is nice but not too necessary since most dungeons are short and straight forward.
4. The inventory management sucks, but the Warehouse is useful. If you can't find an important item that you left on a character, go to the warehouse, select "Strip" and you can check every characters held items, and bring those items into the warehouse. It also helps with storing key items until you meet the characters who need them.
5. Stallion makes you travel on the world map faster.
6. You need a TON of money to level up weapons and buy the best gear for everyone. But it's easy enough to hack Potch after you recruit Gaspar (he's in the basement where you met Tai Ho). Gaspar's dice game is the easiest way to make ton of cash. You save at Mary's Inn in the castle, Gaspar will be running dice right by there. Play the game and bet 9,999 Potch, then do double-or-nothings until you get a giant amount of money...you'll just need to keep save scumming until it works out.
7. You need to recruit everyone before the last couple of story events to get the best ending. It's not as hard as it seems once you've got teleportation. If you have any trouble, there are a ton of character guides online.
8. Suikoden 2 gives bonuses if you have save data from Suikoden 1. Any characters at level 60 or higher who you recruit in S2 will have a level bonus, and if you max out their weapons, they'll have a weapon bonus too. So, pull up a list of the characters that are in both games and do some leveling in Gregminster or the Dragon Den to make S2 an easier run.
9. Last but not least, if you want to level up characters fast, the easiest way is to pull them into small parties. Kai and Tyr for the Unite attack + one or two characters you want to level up = quick leveling for everyone.
10. I'll see what's good with S2 and throw notes in after. I love these games, so I hope other heads can take these notes and enjoy the experience.