I played as white. Following comments I got on earlier games I'm now working through Get Strong at Tesuji and reading Tesuji and Antisuji of Go (which I find a bit difficult). I hope this will help me read out tactical situations with more confidence to make more informed strategic decisions. I would be happy to receive pointing out of bad habits and faulty reasoning!

Thanks & Greetings,
Jorden

I think this is a mistake, since black has no base yet. It doesn't threaten anything, so I don't have to respond there.
Ignoring this was ok, but since black left upper left unfinished I should have played around ghj17.
Now black gets this point..
Too wishy washy? What should be my thinking here? Black should just get the top for nothing, I have to apply some pressure on his group. I was thinking op developing something, but this doesn't really secure the corner (with 3-3 still an option for black). Approaching at m17 better? Then black doesn't get anything for certain I don't as well.
Now the approach at C6 instead. Working this the upper left, also helping F3 group etc.
Any thoughts on what to do here? After my whole left side potential is dwindling fast, and black is expanding there while putting pressure on my F3 group. C11/C10?
This doesn't put pressure on black. It doesn't secure territory. It doesn't defend any weak groups. I was thinking about 'development', but with black R12 possible...
Better to cap at P12. Then black has to worry about living locally. Was this invasion an overplay for black? Also in the sequence till that follows, I wasn't really sure what to accomplish.

Main question:

Ok, dealing with the 3-3 from . After white Q17, black could've played S15 and after white s16 blacks group at p13 would be better/fine. But since black played in the corner, I figured I could kill black. How important was to kill the black group in the upper right? I now see that the other black group at P13 is in trouble as well and capturing that would be more important than killing black (in gote?) as I did now.
So black is dead after at S15? No more white moves needed in the corner?

I feel that after how I handled the 3-3 invasion, black took a big lead and the game was basically lost.

Some comments on the game:

@Skydyr. Thanks for taking the time to comment my game, I'll go and read up on aji-keshi. Very helpful what you did with , giving the options and describing the different aims they try to accomplish.

Aji-keshi is a harder concept apply than it is to understand (I find anyway, like most of Go hehe). Anyway, at 112 - how about something like H17 - then if he connects with G17 you can play K17 and if he then takes you connect out with L17 and will probably eat his five stones. Alternatively he lets you capture at G17 or J18 at one point and you’ll have reduced him by quite a bit? Unless I'm missing something (I should do a fancy diagram but I'm not sure how to get the board position).

Also, you might want to play a few handicap games against stronger players, I think you might have an impression of "territory" that is a bit generous to your opponent - a strong player with white will be able to demonstrate how a lot of aji can be exploited or how "open enough" areas are ripe for invasions etc. Alternatively, look at pro games to become inspired at how cramped they are able to make the Go board most of the time.

@Majordomo, maybe it can be a start to focus a bit more on timing. When is it time too reduce, invade? When is it time to defend groups etc. When can I take a big point. About the territories: I think you are right. I'll see if I can get a couple of handicap games going. Maybe I'm taking territory and development too literally. In a way the opening seems more about threatening to take a bigger piece of the pie ('if you take that, I'll take this') and it doesn't matter how big that piece is if your opponent is getting something a little bit smaller.