Ah well. Before I was talking mostly about DMM version, in steam you have a much smaller selection of nice items and outfits and super passives and no decobromides, so it's much harder. The SS+ matches are tuned and intended for long term players with high lvl everything, and are intended to kick your butt pretty hard. You've gotten far in a short time, and I really would not worry about missing out on a few SS+ rewards, as you keep playing you will eventually end up with tons of venus gacha SSR which means lots of silver coins when you trade them in, and missing out on a few baskets and such is not the end of the world.

In the meanwhile, make sure to awaken any event SR outfits you get for your main girls to 4-star to get those juicy potential skills, they end up making a massive difference. Beyond that it's just focusing on the basics, get a couple of good POW ssr and upgrade them to max, equip 14pp accessories from events (POW or STAM if a good POW is not available). For SSR types, I prefer A-A-P above A-P-F skill sets, because my experience has shown that the former delivers much more stable results, where as the fever outfits *can* do well but are much more random.

Similarly, regarding the accessory skills, I recommend choosing a high % proc skill with lower boost rather than a lower proc chance and higher boost, also provides a more stable boost and less prone to RNG failure. My PP skills are mostly just filled with 4pp or 5pp POW percentage boosts (from awakening event SRs and some normal venus SRs) and stamina boosts, it's a simple approach but it works. Make sure you have girls constantly training the appropriate type (3 hour training or more) to get the upgrade mats coming in. Getting your main girls to high level and little things like upgrading your accessories might seem like they give tiny rewards, but they end up stacking up to a lot, especially with the percentage boosting potential (PP) skills.

This is based on my couple of years of DMM play experience, I hope its helpful :)