football manager gets harder (read as more realistic) every year so when i was able to bring my favourite brighton to premier league few years back, it is not so easy now.
Generally it's absolutely natural that after promotion your first goal is to avoid relegation. In real football there might be some exceptions, but we are talking about clubs with enormous financial potencial. Common thing here in Czech republic is that some industrial boss owns a big factory and sponsors local club, which he can promote through several divisions, until he reaches his financial roof.
In FM2011 you usually get bigger money to be spent on salaries and you should look forward to the date 1.7.20xx. Every season many players are released on a free and you should try to get some experienced guys to strengthen your squad. Again, it is natural that after promotion maybe half of squad is changed. If you dwell on your guys who won promotion, you will experience difficulties. Only your key players can play in higher division well. If you counting on your players to be blending well together, than you can't expect them to play for promotion again.
Anyway you should try to use your first season in higher division to consolidate your team, to work in new players and to prepare your tactics and stuff for next season's attack for higher positions (if your budged allows you to even think about it).
Speaking about reinforcements, you should look for players between 25-31, anyone younger would struggle in mentally tough relegation fights (you will lose many mantches, mentaly stable players are needed with high determination etc) and anyone older may be too short term investment (when the team can get to know him and vice versa he may start to decline).
