There’s no Corinne Tilly card!

Anyway you should know when to surrender when you’re losing and save the big cards for the last round.

The latter.

Focus on northern and Nilfgaard decks. Use and abuse spies and decoys. Ditch normal cards and focus on tight bond cards instead. Scorge is useful to have if you have any at this point. Also, by later stages, a killer strategy is to use hero cards combined with weather cards. Since they won't be affected, you will usually aways have an huge advantage against your opponent.

A huge number, if not all of the truly valuable cards are ones you win from playing, the stuff vendors sell aren't really game-changers. I'm sure there's some exceptions, but almost all of the NPC's that you can play Gwent with also give a card once you beat them the first time, then it's just money if you keep playing them. So to really build your decks you have to beat some people and work your way up to the ones you come across in quests, otherwise major NPC's you can play with etc.

I mainly play with a Nilfgaard deck and heavily abuse spy and decoy cards, intentionally throwing the first round by playing all of the spy cards to get a significant advantage in the number of cards, then crushing the AI in rounds 2 and 3. The decoys are for cases where the opponent plays their own spies or uses a decoy/medic to throw the spies I've already played back at me, so I can just decoy it into my own hand and play it again to get even more cards. Medic cards can be similarly abused with decoys to bring back cards you've played in earlier rounds, or really any card that applies an effect when you play it like the dragon that nukes the opponents melee cards.

Early on with the default deck, just remember to trim the fat by getting rid of low value cards like the Poor Fucking Infantry or Redanian Foot Soldiers, since they do little beyond making it less likely that you get actually helpful cards into your hand. If you play relying heavily on any one of melee/ranged/siege card types, don't have weather cards in your deck that actually hurt most of your other deck, like having several biting frost cards in a deck that's mostly melee. And in general it's not worth it to have a ton of the same weather card at once in a deck, unless for instance you know you're going to play someone with a Monster deck, in which case biting frost cards absolutely ruin them. The cards with the bond effect (the clasped hands) are pretty damn great, as long as you have as many as possible of the exact same card. They can result in some ridiculously OP hands when combined with something like a Commander's Horn card.

For the Northern deck, replace those Poor Fucking Infantry asap with Blue Stripes Commandos since they're quite literally four times better (you can buy these in White Orchard, Crow's Perch and Midcopse), the Crinfrid Reaver cards can also be found in White Orchard and around Velen and you should definitely abuse the siege cards available for the Northern deck due to their overall high point values, you'll get quite a few of them from just playing random merchants and NPC's. For the commander card, instead of the default Foltest, either use the one you can buy from White Orchard or the one you can win at the Royal Palace in Vizima from a Nobleman there. They'll let you either clear all active weather effects to counteract something like a Torrential Rain card that would otherwise ruin your siege engines, or buff that siege row like a Commander's Horn would. In general, both are quite a bit more useful than the ability of the default Foltest.

Gwent?

Never heard of her.

Okay, I am doing well in most gwent games now, finally have some good decks and win more than I lose and have been enjoying the matches, though I did manage to lose in the 1st round of the big city Gwent tourney.

Once again thanks to all for the tips.

Has anyone played the standalone version of Gwent?

If so, what are your thoughts about the recent homecoming changes?

I've been playing since open beta, mainly Nilfgaard mill decks (don't hate me!  ).
For me the spark seems to have gone since the homecoming update this month. It just feels that they've gutted all the different archetypes what made gwent unique and now it's just a little bit stale (it might just be my biased opinion as the mill deck is not as competitive as it used to be).

It might improve with future updates though.