Checkraise flopp if oponent always cbets. Check call if he checks back some air. Checkfold turn if he barrols this turn.
 
If you donk flopp (wich if don´t think you should) you have to checkfold turn. Check calling is horrible IMO, you´re not sure if you´ll get any value if you happen to hit the flush, you can´t bluff if miss and you can´t bluff catch if you hit 7 or 8.
 
If the pot was limped you could donk, if you doesn´t know that villain autostabs, in which case you checkraise.

Effective Stacks: 71bb Blinds 10/20
Pre-Flop (30, 2 players)
Hero is BB with s7 s8
alex4890 raises to 40, Hero calls 20
Flop (80, 2 players)
FLop: s5 s3 dQ
Hero bets 40, alex4890 calls 40
1) idk villains button raising frequency to give any assumptions of whether this board hits villains hand range... but, imo, most likely this board didnt hit much of villains hand range... other than the FD on board, this flop is pretty dry, with few QX combos in villains value hand range here....
2)u have the option of checking or donk-betting... if ur checking, its to check raise, since ur 78s, has zero SDV, and for every following streets, ur FD equity decreases in value. so by Check raising, i am banking on my postflop equity while forcing a fold from villains marginal hand range....
**) i dont hate the DB, since ur still taking the initiative in the hand.... 
 
Turn (160, 2 players)d5
Hero checks, alex4890 bets 100, Hero calls 100
This is a bad card for ur hand range, since it improves villains hand range.... villains continuance range consists of A-high, strong K-high floats, 5X,QX,3X,FD....
basically QX is calling u on turn to bluffcatch, 5X is now trips, which improved in equity value... most A-highs, arent folding now, since its combinatorically less likely for u to have 5X here.......
1) betting is out of question here....
2) ur checking. the viable option is whether to check call or check fold.... ur not folding much with a CR here on turn, since villain is most likely bet-calling u with most of his bluffcatching hand range.....
3)most likely scenario: with flush outs: 9(flush outs)X2=18% equity
ur check calling for implied value of hitting ur 18% flush equity on river
4) check folding, my hand is hard to continue, and im not going to get much value even if flush hits river, since my hand is faceup to villain
 
 
River (360, 2 players)c7
Hero bets 60, alex4890 raises to 420, Hero calls 360
1)????
what r u getting value from?, ur chopping with all 7X, and ur losing to 5X, and QX....
A-high isnt calling u on river, while ur value owning urself..... check call, or bet fold as what happened here....