If you have never played SSF and looking for some advice, then you came to the right place. What's the best way to figure out which uniques are good to farm and can help builds pop off? Are there any good assassin builds for this? Never played one and wanted to give it a shot. Hope these solid tips can help you.
Tips for SSF in general:
1) you should start with a solid build that needs no gear to work, only the first 3 ascendancies, and can go without any difficulty to at least red maps. These include builds such as sunder, SRS, ED, blade vortex, ancestral warchief. You have a long way to progress through the atlas.
2) plan ahead your shaped strategy if you want to have one. Sextants are scarce, uncompleting maps is a nightmare.
3) learn which div cards are worth farming and which are not. As a general rule, I'd say that cards that only drop from bosses are less viable than those which drop from any monster in the map. Some good places to look for target farming div cards include arena for BoR, volcano for kaoms heart, residence for 6l chest, tower for shavs.
4) use all the game has to offer, really. Silver coins, master craft, menagerie, chaos orb on zana mods, alt/regal/exalts shaper items. No PoE Buy Currency should be rotting in your stash, they're made to be used. Don't forget masters daily trade (vorici jewellers to fuses for instance) and vendor currency trades too.
5) do not underestimate lab runs. It provides a lot of currency and uniques. Probably don't even enchant helms in a race unless you wanna migrate eventually, boot enchants are the shit (helm gambling is fun in a 3month league though)
6) enjoy yourself. You are not grinding for anybody but yourself, you have no PoE buy Items, so you better do the content you enjoy. Have fun!